Whats up with this man?

My son (17) will be 18 in May has been dating a girl (16) Her parents didnt like my son so they forbid their daughter to see or talk to my son. 2 wks. later she finds out shes preg. Her parents were really pist. and asked to meet with my son about his intensions regarding her preg. My son and his girlfriend agreed that living together was not a good idea at the moment but that he would be involved with her preg as much as possible. My son works and works hard he doesnt make much but agreed to give her a100.00 a week to help her with what ever she needed. Her father agreed to let them see each other. All was good. They allowed my son to go over to see her they even let him spend the night a few times. after a couple of months they wanted my son to move in and talked about getting a bigger house. My son was all for it but thing is he makes about 300. a week and thats on a good week if weather permits.(works on roofs ) and her father wanted him to pay for half of rent and half of utilities. My son couldnt afford that and decided not to move in but stay at home and save money. Her father was upset about this but they moved anyway and now pay 1000.00 in rent as opposed to the 300 they were paying before. My son has been giving his gf her weeky pay in which she uses it to pay for her clothes and lunch for school. Her father quit buying her clothes and paying for her lunch. my son even pays for her cell phone. She scheduled an appt. to see the doc. and asked for 200. The weather hasnt been to good so he hadnt worked. so he asked her to reschedule her appt. for the following week to where he was able to give her money. weather was still bad so he was short only made 60. I asked about him about her application for medicaid but her parents are to busy to take her to turn it in. The other night my son was talking to his gf and her father got on the phone yelling at him and even threatned to kill him. he was upset about my son not having the money to give her. and demanded he meet him the next day. He told me not to get him a xmas gift and instead give him the money to help her. I felt bad for him so I gave him the money I was going to use on him so he can give her. Yesterday, I took him to his gf house so that he can give her the money and she said that her father wanted to talk to him and to give him the money. So he went to meet with his father at his shop. I stayed in the car and let my son go in and talk to her father. Next thing I know his gf little bro. comes out and tells me to go and get my son. I get off and find this man yelling at my son pointing his finger at his chest and face. my son wasnt yelling back at him. I told my son that we needed to leave but my son really wanted to talk things out cause he didnt want her father to not let him see her. He accused my son of not giving his daughter money i vouched for my son cause ive been there when hes given her money. I told him he needed to talk to his daughter. He accused me of lying. My son tried to give him the money but he refused to get it. I got upset and and told my son that it was best that we leave. so we did. We immediately went back to his gf house so that he can give her the money. My son told her that the meeting didnt go to well. She already knew about it cause her mother called her and told her about it. and now they dont want my son seeing her. she had to give back the cell phone. They said the only way she can be with my son is if she moves out. After talking with my husband we decided that was ok. as long as her parents agree in writeting since she is 16. but now they are threatning to file a restraining order against my son. . this girl wants to be with my son.but is terrified of her father so she does what he says. My son is now so depressed and doesnt know what to do or how he can talk to her.He wants me to talk to her father but I dont know if I should. Since her father is such a jerk. and gets off by bullying my son and his daughter. What should I do? and should I or my son file a protective order on him since he threatned my sons life not once but twice.? her fathers on probation by the