You asked about boundaries. No one can tell you what your boundaries are so it's best to read up on these in that first post Cadet sent you. While it is agreed here that physical and emotional abuse are not acceptable, and that we should always protect ourselves financially, beyond that, what one person will tolerate another will not. Some will stand through multiple MLCs!
In general if this is MLC and you're trying to save your m, it's best to sit as still as possible because you're not really dealing with a rational person. In a rational world you should be able to go to your spouse and say "what gives? Why aren't you depositing your pay to the joint account?" With a MLCer you should be prepared that calling her out on anything (and I mean anything) could cause a very disproportionate reaction: like she could file and take 50% instead of 30% and you could be seeing your kids 50% of the time and have to sell a house if you own one.
Again, not at all fair, but while you can try to set a boundary she has the right to file. So weigh it all carefully.
You definitely want to be protecting your assets though. Put alerts on your accounts, watch credit cards, run a credit report, etc.
Another option is to talk to a few lawyers about what she is doing and how the court would view this in a d. (Usually they give a free consult.). Perhaps what she is doing can be viewed as hiding assets and it might come back to bite her! Perhaps you can also ask if you too can limit how much you deposit into the joint account to protect yourself?
But seek counsel first because I do think sometimes it can look suspicious/like you're hiding money.
Me 41, H 47, M 15 yrs, S11, S13 BD 1: 11/4/14 we work on it; really I pretzel myself BD 2: 3/31/15 H goes down to "dorm room" 8/15: H back to MBR 10/15: H back in dorm room 1/18: H files, now divorced