This is a very complex family dynamic. When things are running smoothly, I get along pretty good with my foo. It's been really difficult, however for about two years.
Two years ago you began your recovery from co-dependence, and two years ago your relationship with your FOO began to get difficult. There's no coincidence there. It's to be expected. You began to change your role in the FOO, and that shook up the dysfunctional FOO apple cart.
I'm not seeing how this family dynamic is complex. What they're doing is the standard dysfunctional family's response to one family member's pulling away from the dysfunctional family system. Did you believe you'd be able to do that and your FOO would just go along with it and become healthy, too?
Consider this: the reason you're perceiving it as "difficult" and "complex" is that you've got some conflicting internal agendas going on inside yourself. You want conflicting things, and you're trying to find ways of controlling what the other people involved (H, M, SD) do so as to make it all happen.
You want to be mentally healthy. You want to relate to people in healthy ways, rather than from co-dependence. You want to have a relationship with your FOO, and you want that relationship to be "smooth". You want your H to be a part of your relationship with your FOO.
You just want everyone to get along, darn it!
Seriously, the things you want are understandable and reasonable. The only problem is, your dysfunctional FOO cannot give those things to you, and you have no control over that fact.
My husband was trying to tell me what you've both written but his style was aggressive and bullyish. He was scared and could not allow me time to process my awakening in my own way. He tried to control my recovery and it ended up backfiring, sending me directly back to my moms arms.
I hope you don't mind me being blunt here, but when you have disagreements with your H, you should not be running back to your mom's arms. That would be true even if your M was emotionally healthy. Work your marital relationship problems out with your marital partner. Your priority now should be attending to your own marriage, and your responsibilities to your children; not trying to manage your mother. Your primary family now is the family you're creating with your H, not your FOO.
I'm just unsure how to handle my mom at this point.
This question gets us to the "nitty-gritty" of your situation. I would suggest, for starters, that you stop trying to micro-manage everything. Stop bringing your H into it, trying to make your FOO fit him into their family system. Stop trying to "handle" your mother, actually.
It sounds to me as though you are still emotionally enmeshed with your M to some extent. You're still taking responsibility for her feelings, for instance, which is pretty common for us co-dependent types; and you're still afraid of her responses, which if you're dealing with an N is very understandable. You're early on in your recovery path, so don't beat yourself up about this. Just continue to work on distancing emotionally from her. I can't remember if you've said whether you're in therapy, but it could be helpful at this point.