You might ask her if she really wants to attend the wedding. It sounds like there is a real risk that she might ruin your son's wedding or cause significant distress and disappointment for the bride and groom. If you can somehow make it that your wife decides on her own to opt out of going to the wedding, that might be best for everyone concerned. If not, I don't know what to say, as you really can't control and predict her behavior. If she is going, I am sure there will be others on this board who will have some helpful suggestions. Keep us posted on your thoughts and what is going on!
Not having her go is actually what I would prefer, given the circumstances. Would I like her to be there, and for us to have a great time together? Sure, but history has taught me that's not likely.
Virtually the entire time I will be on guard to try to keep triggers away from her and stand watch over her. And then deal with what I believe is at least a 50/50 chance that she will be upset with me (to say the least).