While I agree with sixthson's comments and advice, I confess that I did not routinely follow them when I was single and closeted.
I fooled around with my share of guys. And, yes, on more than a few occasions I did bump into them in public places. Sometimes they even had wives in tow

(some of whom I knew about, and some not lol--oh well). Anyhow, we just nodded heads, or muttered a brief "howyadoin'" and moved on--like you would any acquaintance from the neighborhood, the gym, or work. It's not like either of us loudly proclaimed "Gee, I've been thinking of you lately--I'm so horny! Sex with you was the best yet!" or anything! lol You just play it cool. I've even run across people shopping that were alone and I was alone. Again, "that topic" never really came up. When you're in a public place, you keep the party manners on. We sometimes just did the nod or "howyadoin'" thing, or, if I really liked/knew the person, might catch up on news of the day--just like any normal guys would who hadn't seen each other recently. It never attracted any attention at all.
I've run across guys who were so closeted that they had all sorts of doomsday scenarios built up in their mind and they became so paranoid that they were paralyzed into not doing anything. I guess that's a shame, although others might think that's a good thing. I don't know. Anyway, sex is infinitely more fun when it's with someone you know well/love and when you aren't deathly afraid of seeing the person again or getting caught.
Good luck!