Custody of my baby (in laws)

Mayra • 🌻☀️🍕
I live w my in laws. They control everything in my bfs life. When they first found out I was pregnant they were talking about getting custody of the baby. Even thought I have never showed I am a bad person that does bad things.  And if we don't do what they say, they get butt hurt and bitch about how horrible me and my bf are.
 My FIL saw that I owed $1,000 on all my bills. He handed me $1,000 and told me to pay my bills. And that when I started working I would pay him $100 a month. I'm
On unemployment at the moment since I am two months away from giving birth. I get $131 a week and will be giving him $100 a month starting today. But, I want to create a contract. Since my FIL won't sign it and will get offended, I'm gonna have my bf sign it. Another reason I want my bf to sign this is because he always tells me that I am stupid and incapable of taking care of myself. And I am afraid that if one day, his parents don't like something I do, they will raise hell and convince him to leave me and take the baby from me. Knowing my bf. He will reason with them and not me. Even though I don't do drugs, drink, I go to school and work when I can. My question is... What can I put in the contract? 
Can I put that I am capable of taking care of my baby no matter what they say? I also wanna put something like I am not here for money. 
Thanks for the advice.