How long has this been going on? - With her going back and forth between him and you?
I also see an advantage you have. If they fight all the time, you can be the more attractive man she will want - but it is going to take plenty of DBing techniques - which is doing a lot of permanent 180's so she can see for herself which is the better choice. That's the best I can do for now to explain it, but in the end our W's will need to make their own choice. It sucks, I know. We are here for them, but it is up to you to decide how much you can take.
I was ready - and still am - to leave my W if I knew that she wasn't truly committed to the R/M because of her hanging on to OM. I have been told to ride it out, that she will come back to me and in time let him go. Right now it seems hard to believe and difficult to swallow. All we can do is bite our tongue and patiently let this all play out - but each one of us has their own breaking point, right?
It comes down to one question:
* Do I want to save this marriage?
Lots here to digest.
~Sol
~~~~~~~~~~~~~ Single Dad, and luvin it! ~ Happiness is a state of mind ~