Wow! I haven't kept up with your sitch Olive. I'm so sorry to read this. I can fully understand your feelings about this. I felt the same exact way. In fact, and I don't say this to make your situation any more difficult.... but I used to tell my husband I would NEVER agree to a 50/50 split because I believe kids need to have their own home (not two separate ones).
Fortunately my husband was willing to do the every other weekend thing. But I did tell him if he wasn't going to do that I would let him be the main home and I'd take them every other weekend. Quite honestly, I think that idea scared him more then anything. I remember during the divorce telling him I was going to move to Florida and leave him with the kids. Boy did that make him livid!!!
Truly, I don't think I could do that. My kids are my life. But I would put their welfare before my own.
Anyhow, hang in there. You'll have to figure how much you want to spend on this issue. I'm glad you have your parents around. {{{hugs}}}
There is no arriving, ever. It is all a continual becoming.