Although it's difficult, try to make light of it when it happens. Don't let it take your life over.
Personally speaking, I'm a straight guy...if I was talking to a girl who was blushing I would think it was charming. It wouldn't bother me at all. It really wouldn't.
If you can relax just a little and maybe make a light hearted comment about it when it happens, it can take the fear out of it. This is important because it sounds like you're beginning to get caught in the anxiety loop. At first you'd blush because of genuinely embarrassing or stressful things, but now you may be blushing because you're worried about blushing!
It's a cycle that can be broken. It takes time and determination but you can do it.
I have to laugh at myself all the time...it's taken years of practice
