I totally get that feeling of not wanting to spend the time and money on something you feel should occur naturally and frequently without a third party. I don't go to marital therapy anymore, either, and that's a big part of the reason. I felt it was a crutch.
I do feel that your current situation is different. The goal is not to improve your marriage for its own sake, IMO, but to reach an equilibrium that will be healthier for ds, b/c I would consider the current tension to be something of an emergency. If it's bad enough for you to run away, it's an emergency.
Plus your dh sounds like a stubborn guy who needs to hear from a man that his behavior is unmanly and unacceptable. Unfortunately, some things, a man can only hear from another man, and it sounds like dh and ds are two of a kind in that respect. Your dh needs to man up, and it might take another man to make him realize that.
Keiki's Makuahine (Keiki's Mom) 51, dh 52
Keiki: b. 2002 after 3 months bedrest
Natural conception following ZIFT/chem. pg
Olivia: b. 1999 d. 1999
28-week preemie, ptl cause unknown
Natural conception after 1 mc
ttc since 1998