HaWho I don't know how you've done this for so long. My H comes over for a half hour after months of being AWOL and he is on my last nerve.
My kids are a little older. They both let me know that they didn't want my H in the house any longer and that gave me the power to make him go. I'm not going to lie, they have suffered. D is in her senior year and failed a class at midterm and got a D in English, in which she has always had As. Fortunately it wasn't a disaster because she is going to a conservatory and all they care about is her musicianship. She is going to the best one in the world, so it worked out OK for her. My S was a straight A kid who cried if he got less than a 97. Now he doesn't turn in work and gets a smattering of As, Bs, Cs, and even a D. I'm still hoping for a turn-around before 9th grade. I wish my H had done his disappearing act in the summer. I think it would have been easier. Instead he did it at beginning of October--worst possible time.
Kids are bouncing back. Ds grades are back to normal. She has 3 weeks left. All looks good for graduation. S is coming back more slowly but when she is away next year I'll sit on him for a while.
I guess I'm trying to say if you do decide to give him the heave ho, the kids will survive. Having one parent who loves them and supports them unconditionally helps. They know I have their back. We are the three musketeers.