Depression can take on so many different symptoms for each individual that it's difficult to say that "yes, that's definitely what it is". I could probably feel
at ease with saying that it's likely that pushing you away is part of his problem
with depression, and I think your brother's being in the home is a major stress for your husband. It can create a very difficult situation for everyone.

Psychotherapy is called for, in my view, to re-establish the close relationship between you and your husband as the "we" in the home. I hope you both
will find it to be very helpful in your relationship and that you will be able
to remove whatever is causing the distancing between you and your husband.

It sounds as though you really had a good thing going for both of you for
years. So sorry this is happening, but it is amenable to treatment for both of you, and I hope that works for all-round improvement in living.

Take care.