Hi IDBG, I just read through some of your other threads to get more back story.
I don't think you are being "stupid" for taking the time to consider what's best. However you could probably safeguard yourself and D4"s financial future a bit by not leaving yourself wide open to financial problems.
You say she won't discuss things, but I assume you can text/ leave a message right? If i were in your sitch i would leave a voicemail (in an upbeat tone) that says you want to make sure her and D4 are well taken care of during this transition and that you'd love to hear how much she's going to need in the near future to help her get by. In the meantime get a new bank account for incoming checks for yourself and only keep limited funds in the joint account for her. I would tell her you'll be closing the credit card accounts by a certain date and to let you know if she needed you to extend it for any reason.
Let her reply and if need be try to negotiate a bit. Give her the sense that you want to help her while slowly reigning in her access to money.
Typically in a true walkway wife scenario I wouldn't offer so much financial help, but in your sitch since infidelity is involved I think you want to give her space and time to figure out how to forgive you.
BD: Aug 2012 Separated since May 2013 S born Aug 2013 Aug 2013 H agrees to consider 'baby steps toward working things out' H is/was actively seeing someone?