Just Wanna Have The Information Before Everything Else

So my husband asked for a divorce about a month ago. Neither of us filed for anything yet so he wants to make an agreement before filing. We have a 4yo child diagnosed with autism, he’s non verbal. Since he was born I became a stay at home mother and he worked and provided for us alone. He’s trying to make to go to my home country because it means he would have to pay less to support his kid. I’m a legal permanent resident here (Massachusetts) and I don’t want to go, my son is doesn’t have my country citizenship and couldn’t go with me before going through the naturalization process. He’s saying he will help me move on by letting me keep one of our cars and wait for me to get a job. He has a union job and gets very well paid. I’m limited to what kind of job I can get because my son goes to pre school and is about to start ABA therapies for his ASD condition. His father does not want his guardianship in any circumstances, he just wants to be with his son one day of the weekend. I don’t trust his mouth agreement that he’s gonna help me and every time I say we’re going to court he feels threatened and says I’m not going to get any deal better than what he’s offering me. He says I’m not entitled to alimony or anything and the child support will be way less than what I think it will be. I don’t know how the legal system works here and I know a lawyer will cost a sum I cannot pay. I’m starting to get desperate cause he keeps pressing me to make a move but I don’t have family and anyone here to help me. I don’t know what to expect from the court either. Any kind of advice or piece of knowledge is really appreciated.