Not that I'm (necessarily) suggesting this, but a divorce might be in your favor because you have children (i.e. you probably won't end up "homeless"). See what your therapist suggests. If you do go forward with a divorce, make sure that you have a good lawyer.

A part of me agrees with hamster-bamster regarding collecting evidence (can't hurt, right?). After all, your husband lets your son use the computer, and he knows that you know the password.

I wish you and your family the very best. Good luck.