I would keep your current T just for you and go to someone different for your marriage counseling. Cause your T is for you-he is your support system. T's do know how to be a neutral party when they need to be but if there is ever a situation where he validates what your SO feels or anything like that-it may create ruptures between you and T. I don't know-I've never been in this situation-but its just something to think about.