First of all, take it easy on yourself. As much as it may not feel sexy, farting is a thing that happens. Also, we sometimes forget that while sex is, yes, hot, it's also sometimes silly, funny, absurd and ridiculous. Don't be so hard on yourself.
Besides, because it sounds like you are only experiencing the excess wind in the context of sex, I suspect your level of stress may actually be making it more likely to happen! What can happen sometimes is that as we build toward orgasm, is that we tense up and unwittingly bear down, which has the effect of pushing gas out of your lower bowel. If that can happen when you aren't already tense about the possibility of breaking wind, imagine what adding stress is doing!
So, my advice to you is to stop thinking about the wind and try to focus on all the pleasurable feelings your body is experiencing. Don't think about trying to make an orgasm happen; that can cause you to tense up as you try to "work for it." Instead, try to let yourself go with the flow and get back to enjoying sex and masturbation.