How to get out of a toxic relationship

I’ve been in a relationship with a man for almost 7 years. We have a 4 year old son together and my daughter lives with us full time as well.
I feel he belittles me, and we just have different ideas of what it means to be “happy.” I’ve tried everything I can to make it work, but I’m just not happy.
When we first met, I had a house, and he lived in and we split the bills. After our son was born, he thought we needed a bigger place, so found another house and moved. However, his VA loan wouldn’t put me on the mortgage since we’re not married. But I still pay half the mortgage and put a lot of the proceeds from the sale of my house into this house. If. I leave, I lose all the equity I’ve put in, and he has said multiple times he will fight for custody of our son. Our relationship has been rocky for years.
I’ve talked to counselors about this, tried to make it work, but it just won’t. Emotionally and mentally, I can’t take any more. But, logistically, how do I do this?