Then you had better do that first thing. We've seen many times when the WS is deep in the fog of their affair, that they will clean out any joing accounts and run up any credit cards.
You also need to consult a lawyer and see what your options are and try to get an temporary child custody order. Never just assume that children will go to the WW. And get the morality clause into there, that OM cant ever be around the children, with you mentioning is PTSD issues, that would help bolster your case.
If this OM has been in your marriage from the beginning like you describe, then this is yet another one of those cases that the entire marriage has been a lie. This is seen all the time, where the WS only settles with the BS (you) because they are the stable one, but keeps their former lover in their heart. Sorry to have to tell you this, but she only married you because you were there, while he went off into the military. She would have gladly married him if he didn't go away, you were only her second choice. We see this type of situation all the time here.
Since OM is divorced, there is no OMW to expose the affair to, but you can expose it to family and friends. Whether she admits it or not, she's been in a long term EA with him, so she's been very deep in the fog for a long time, which explains why she's been witholding sex from you. Sorry that you're in this situation.
I would say your chances of R are slim to none because OM has been involved in your marriage from the beginning. She's been in contact with him the entire marriage, provided a shoulder to cry on, and confiding their most intimate marital issues for him. It sucks to read another story where the WS has been with the OP before the marriage and all thru it the whole time.