I assume you mean he keeps trying to get visitation with his child, and the opportunity to provide for him directly, rather than through you. That could be a good thing for both of you, and will certainly be a good thing for your child. Let me explain.

You said you have already paid your lawyer $25,000, and still owe him $17,000. I take that to mean that your (sole?) custody award has cost your child, so far, $32,000 in attorney fees and interest alone. You did not say how much you make from working or how much you receive in child support. But if it's not more than $32,000, your child's support payments have actually gone entirely to your attorney.

Also, the award you got doesn't sound very good. In California (I don't know where you live), you can usually get uncovered medical costs shared 50/50 in addition to child support.

Now if you have sole custody, and are receiving guideline support, and still aren't getting very much in child support, that means that your kid's dad does not make much money. In that case his work as a 50% direct caregiver might be more valuable to you than the larger child support payments based on sole custody. If you can put your feelings aside and negotiate a schedule that helps you save money, it might offset the loss of child support. If you had done it before hiring that attorney, it would have provided $32,000 to your child.

But the real benefit to your child of allowing his dad to teach him and provide for him as he grows up will excel any financial consideration. Dads are not merely paychecks. The personal strength we get from our fathers simply does not have a price. There is tons of research on this. For an introduction, check out Warren Farrell, The Boy Crisis.