22 years old, and really curious, but very nervous. Help?

So, as stated in my title, I'd really like to try sex with another man. I've identified as straight most of my life, but the past few years I've sort of declined to identify (just because I don't feel comfortable being labeled). When I was 13 I had my first homosexual experience with my best friend at the time, which was very exciting, but it made me feel really bad about myself and really dirty (in the bad way, like I had to take 2 or 3 showers to feel better).Anyways, skip to today. I just ended a 2 and a half year relationship with a girl I was very much in love with, and we've talked many times about my sexuality and how it would be good for me to explore it, and I'd really like to explore it more, but there are a few hangups.I am VERY turned on by the idea of servicing another man and letting him use my body for pleasure, but as soon as that thought turns into actually wanting to try, I begin to panic. My throat gets dry, I lose my erection, my heart beats out of my chest, and I find it difficult to breathe. Obviously not the sexiest situation.I'm worried that having a full-fledged gay experience will ruin straight sex for me.I'm worried that I'll hate it so much that I'll be emotionally scarred by it (my experience when I was 13 messed me up emotionally for the rest of high school).I've watched a lot of gay porn, and I'm turned on by gay porn, but as soon as I finish, I'm a lot less into it, as opposed to when I watch straight porn. I'm really at my wits end and I'd love to try it, but does anybody know any ways at all of getting me to calm down?Also, how might someone like me go about finding someone I can be comfortable enough to try this with?