Hi, I'm new here and maybe my two cents aren't welcome but here goes. I had srs in 2004 and the journey before and after has been fraught with ups and downs. A few of the very best years of my life were experienced after transition. So were a few of my worst.
To the OP, all I can say is I really feel for you. He wasn't the first friend who'll hurt you and he won't be the last. He was certainly a jerk and doesn't deserve you for a friend. You know that. You'll keep telling yourself that for every friend, past, present and future who'll betray your trust. I only hope you have a network of supporting friends and family in whom you CAN trust. Do anything you can to hold on to that. You won't be able to bear the pain without them.
As far as the best advice? A few years ago, I'd have recommended not telling anyone but maybe a prospective lover and I'd have been adamant about it. Now, I'm not so sure. One of my more recent experiences was my participation in a predominantly male dominated activity. I belonged to that group for two years before someone discovered my "secret." In spite of being very popular in the group and well liked, one person did some searching on the internet. In spite of my best efforts to not reveal anything through social networking and personally identifiable information, someone had enough suspicion to "investigate." You just can't run from public record. The pull away from me was palpable. The friendly kiss_on_the_cheek greetings ceased. All conversations became awkward. The pervasive fear of impending physical harm was more than I could bear. I left the group without incident a few weeks later.
The point is, in this day and age, it may be unreasonable to expect pure stealth. Especially with the popularity of social online networking and readily available public record. I think there is a good and valid argument that one should try and forge as many friendships as possible. To withhold your "secret" is to project a dishonesty in the eyes of many. I think it unjustified, but it matters little. People will think what they will with or without righteous justification. Yet, I still find it difficult to bring myself to divulge my past. Somehow it seems like that simple act alone nullifies being a woman.
For me, it's a trade off. Do I sever all ties with my past (most of that was kindly provided by my loved ones) and provide myself the best chance for a successful transition? Or, do I try to hedge my bets by taking satisfaction in the physical aspects of transition and openly pronouncing, "I'm a transsexual?" This is what I've discovered to be an unspoken, unexpected and undesired reality about transition. I'm not sure what the answer is, but I will say this... living without a stable and reliable social network is the most unimaginable pain one can endure. I contend it's even worse than the pain of gender dysphoria because at the heart of our transition we desire above all else, that people accept and love us for who we are. It is the hope of that that keeps us working toward transition.
How we achieve that social network is uniquely our own path. No one should fault you for doing what you have to to meet that end. My sincere best wishes.
Cher