Sorry you are her TA. It [censored] a lot when your stability and what you thought was your future gets torn from you.
With respect to filing for separation, please take time to think about what you really want and what you can/will tolerate before you act. If your husband came home tomorrow and said he was sorry for his mistakes, would you take him back? If so, and if you still want to stand for your marriage, then please please please do not file for anything - let him do it if/when thats what he wants or you do it with you are 100% sure that's what you want. By 100% sure, i mean with a rational mind, not an emotional one.
Believe everyone here when they say time is on your side and do not do anything to accelerate the timeline. Even after a D is filed, there is still time. I made the mistake of filing during an emotional time. Both as a tactic to get my wife to re-commit to the marriage. I was emotional and thought I would fire back and take control of my life again. It failed miserably and now we are that much further along. Furthermore, I acted instead of making her responsible for what she wants.
Do not do anything until you are really ready.
Me:38 W:39 No Children BD: 5/13 EA/PA Confirmed: 7/13 W Moved out 12/13