My XH was so caught up in his own nonsense, he did not secure adequate representation. Worked out great. DS's interests were front and center, and ultimately I got everything I asked for.
My job is to protect DS and myself. For me that includes being fair, so that someday I can answer DS's questions honestly and openly. However, it does not include thinking for or protecting XH, which more often than not, is at odds with protecting DS and my emotional and financial wellbeing.
I would encourage you to step away from sheltering/protecting your STBXWW. Your needs are important. Focus your energy there.