Dianne,
I'm so sorry about your aunt and your marriage. Words can't begin to express how much I empathize with you right now.
I feel that my advice probably doesn't hold much weight, but it would have been right if you, your husband and your step son could have sat down together and discussed his finances, his lease, the options, money, relationships, etc. That would have been the most respectful and loving thing your husband could have done for you.
It seems your husband has cut you out of his private life. There could be a number of reasons for this, maybe he doesn't trust you because he knows this is a touchy issue between you; maybe because of the pending divorce. Maybe he feels obligated to help his son and feels like a failure in your eyes because he feels the need to heip his offspring. I think he knows its not wise, but feels compelled somehow to help his seed survive, sort of a primal thing. The son was there first and seems like "his problem" not yours, his onus, his albatros, not yours. Maybe your husband is trying to protect you from his son by handling these things covertly hoping they will succeed so he can say, "See? It was done behind your back, but it worked."
Your husband is wrong. When something like this happens, intimacy is lost. Another nail is hammered into the divorce coffin.
The son surely knows this and how could he respect you or his father and allow his dad to go behind your back?? What kind of lesson is your husband teaching his son?? That is you are in relationship with a woman its OK to hold back areas of your life from her? It is a total lack of respect.
Satan loves covert activity. That's where he does his best work, in the dark. Complete honesty, no matter how painful, is the best and only option.
I think you were wise to consult your attorney first because when trust is broken and the love feelings start to numb, then survival of the fittest takes over and it can be brutal in the fear of loss of material things rather than working on intimacy and relationship.
I'm so sorry you are about to lose a confidant. Unconditional love is one of life's greatest gifts but maybe when she is with the Lord, she can petition in person for you which is something it sounds like she would do.
Thanks for letting me share my thoughts and feelings.