This is a tough one, because it seems as though everyone has their own ways of working through triggers.
For me, I made the decision early on that I really couldn't use my WS as an immediate crisis support person for a trigger when it is underway. Doing so would have exacerbated the trigger even more, as my WS was the exact SOURCE of the trigger to begin with..! So, I was determined to find a way within myself to deal with it, and then once it passed or I processed it, I would talk to her about it on some occasions (depends on if it was even worth talking about after the fact or not).
I have found that walking works very well. I know it doesn't sound glamorous or new-age, but that is what I did. Just start putting one foot in front of the other.
OK this may sound weird, but this is also what I would do in times where walking wouldn't work by itself: I would actually envision myself back in a previous relationship I have had prior to my M. But only the good parts of a previous relationship (meaning, I wouldn't think about how an ex-GF and I broke up, but I would think about having fun with that person, doing cool things, etc.). It isn't to suggest in any way that I desire that person or relationship anymore, but for some reason it helped REMIND me of how a GOOD relationship should feel, and how much fun and excitement there is. And before I knew it, after maybe 30-60 minutes, I was completely over the trigger. It was pretty cool, actually.
As of recently, I've noticed that my triggers are MUCH fewer and farther between. It really does begin to get more and more gradual as the WS does more to be honest, forthcoming, disclose, and you have NO MORE DISCOVERIES. That is the big one. If you are still discovering shit out about the A (maybe that they previously denied, etc.), it can start the clock over in a lot of circumstances.
Hope that helps!