hey - glad you asked for info/support. from what you've posted, it sounds like you're gonna be more than OK.
WHY I'M RESPONDING
I was diagnosed with HIV in 1991, when I was 28 years old. It was 50/50 whether I'd live to 30 - but now I'm 48 (which is old in gay years, but most days is better than the alternative) and have no real health problems related to HIV.
I'm an RN, and I have volunteered or worked in HIV/AIDS much of my adult life (my last job was educating/supporting people just diagnosed). So I might know a thing or two - and I'm careful to not present anything as a fact if it's really an opinion. (I hope my screename, which is a relic from a specialized adult networking site, didn't make you discount my response.)
HOW IS LIFE DIFFERENT?
in most ways, it's not.
-I take medicine once a day, 4 pills for HIV (and a some for being older and having mild high blood pressure, etc).
-I feel guilty when I don't take my medicine. very guilty, cuz I'm an RN and know better. luckily, missing a dose a month or so hasn't led to resistance/mutations/changing meds.
-I have to have "the talk" with hookups and/or dates - I've come to get it out of the way early, b/c even now some folks won't date someone with HIV (unless they lie or don't know they have it, of course) and I don't really wanna learn that on the 5th date.
-I consider each year a gift (not all Polly-anna like, tho, and I still waste time and make stupid choices in men, etc); since 1997 (when effective meds came into broad use) I don't worry I'll die early, but I also plan in 5 year increments.
-I try to keep everything in perspective. Sure, I have HIV, but I also ride a motorcycle. Which is far more likely to get me killed (but it's fun).
you asked about side effects, transmission/prevention, and stigma - so I'm gonna address each of these (sorry, this has turned into a very long response, but I am too lazy to edit any further and I don't want to not share something important, since we probably won't chat all the time about this).
MED SIDE EFFECTS
-in the medium and long run, many people have few/no side effects. I and most people I know who have been on HIV meds for over a few months don't have any noticeable side effects. You'll hear about fatigue, nausea, "g.i. issues," vivid dreams w/ one medication, etc - but don't presume you'll be in the group that experiences these things, and remember that these types of issues can have multiple causes.
-in the short run, most side effects can be managed/minimized (e.g., taking the med with a type of food that reduces poopyness).
-most med side effects lessen or disappear within a coupla months on the med.
-a great HIV medical source, which you probably know already: Thebody.com
TRANSMISSION/PREVENTION
-there are no confirmed or even very likely cases of anyone getting HIV through "casual transmission" - which includes kids biting other kids, people bleeding on others, first aid when barriers like gloves weren't available, kissing, sharing all sorts of things (like toothbrushes - ick).
-you probably learned about that in health class in high school, but even if you "know" that it's not a real risk, your concern is 1) very normal when someone's newly diagnosed, and 2) shows that you care about others.
-in 20 years of having HIV, I KNOW (cuz I've checked when there was a question, e.g. when an ex got HIV 6 months after the breakup but we only had safer sex and he barebacked with a few poz guys during and after our time dating) I've never given anyone HIV. Which is really important to me. -In this time, I've been sexually active but usually not super-slutty or super-popular, had a brief period of drug use (not the best thing to do if you have HIV. or if you don't), have played sports that involve occasional injuries, and am clumsy (2 bandaids on fingers right now, oops).
-for things like cut fingers, consider whether your blood or
are going INTO another person, and how much. it's EXTREMELY unlikely that you'll infect anyone unless you have sex or share injection supplies. if you bled all over someone who didn't have open sores, that's gross but won't give them HIV. and if they did have open sores, given they'd be oozing out, your blood wouldn't really be going INTO them - so really, this isn't a probelm (but still try not to bleed on your friends. or strangers.)
-the undetectable viral load* - transmission connection makes good sense, though it's not been "proven." Studies strongly suggest it does reduce risk significantly - but not to zero.
-using condoms, at least w/ anal sex (or vaginal, but you have a bf and download gay porn so I think that may not apply to you), reduces risk to zero or damn near zero.
-even if you and the bf have the same strain, reinfection isn't helpful so condoms with him would be a good thing. as well as with anyone else.
STIGMA
-Having HIV doesn't mean you're gross, or a whore, or a party boy, or anything. In fact, one can be all those things and not have HIV or any other STDs, if you use reasonable precautions.
-Try not to judge YOURSELF harshly. Cuz if you do, you invite that from others. And it doesn't help you stay healthy or happy. You made a mistake, as all people do, and you caught a serious but manageable disease.
-I realize your local norms are different than my experience in DC, but in the 1980s and early 1990s, a fair number of brave people with HIV/AIDS have stood strong in small towns, faced prejudice etc. head-on, and made things a bit easier. People may still have an immediate icky reaction, but when they either remember what they know or get educated (by you, possibly) the vast majority will respond rationally and without fear/judgment.
-A good source to learn about the societal issues around HIV: poz.com and/or the print version of the magazine.
A COUPLA THOUGHTS ON SHARING THE NEWS
-You mentioned your friends "are finding out" - do you mean someone other than you is telling them? I'd strongly suggest whoever that is shut the fuck up and let you do this right.
-Tell people who can handle the news and can offer you some support - you may have to educate them; sometimes it's best to wait on telling high-maintenence friends or family until you're a little more "settled," so you don't end up supporting them instead.
-When in doubt, don't tell someone just yet. You can't untell them, and unless you're gonna have unprotected sex or share injection supplies, or they are part of your healthcare team, it's really not their business.
ONE LAST POINT AND I'LL STOP, PROMISE
-Though you may well handle this with friends, family, the bf, etc, if you don't have a counselor/therapist it might be wise to consider at least short-term - maybe a counselor, a support group, or something else.
-This is not because you are crazy. Living with HIV (or Diabetes, or heart disease, etc) is an adjustment. Give yourself time and space to handle it, and get supports as needed.
Hope this was helpful to you. Keep reaching out; people are often better than we expect (given I said "often," that could count as a fact but I don't have stats on it.)
Kevin