HP: You and I sound a lot alike in that we're both reactive. I affectionately referr to myself as a "hot head", but I know it's one of my flaws and I try to reign it in.
Shortly before BD, probably six months before, I went to my primary care doctor and got put on an antidepressant for unrelated issues -- it's an off-label prescription, meaning it's treating another, approved diagnosis (PMDD in my case, you don't have those hormones! ;)). I found that it actually helped me control my reactions. I was better able to think, calm down, and not be so quick to let my emotion in the moment dictate how I acted.
It was signifigant a change that BF noticed it and stated more than once that I had "changed for the better" since I got on it. Unfortunately it came far too late to make a difference to stopping a BD in our sitch, but there you go.
Are you seeing an IC? Can you ask if there's something that might help your moods?
ME: 38 BF: 40 T: 10y, no kids, no M (by choice) BD: 7/14/14, BF admits to PA, wants out, lies about new R. 10/1/14: I move out, BF lies about move in with OW 12/4/14: OW confronted, reveals all the lies