Should I worry about him going back

I'm really scared for my son. I got a lot of good advice from you guys from my last post. My son and I had a falling out because once he started hanging out with this guy he got super disrespectful towards me. He moved out and him and the guy started a relationship. It was very abusive. He put his hands on my poor baby and tazed him in the neck with a stun gun. My child came to my house at like 3am and he was swollen and hurt really bad. His boyfriend had beat him for trying to leave and raped him and put objects in him... I cried when I found out. He had blood on the back of his pants, but he refused to go to the Hospital or call the police so I had him strip and cleaned him up best I could. He's been back home and yesterday I asked him to plz stay here and move back in. I did talk to him about therapy and he said he would think about it. Well this guy has been texting him thia morning saying he's sorry and wants to work it out. My son hasn't been responding, but it seems like he wants to respond. He hasn't blocked him and keeps reading his text. The most recent one he sent was him saying "I know I fucked up but you need to take responsibility too. You weren't perfect in our relationship ". I told my him to block him, but my son is saying he's right and how he wasnt perfect. How he didn't do this right or that right. None of that makes anything that man did okay! Now I'm worried about him going back. How he's talking about it now is like he's blaming himself. I'm worried about him going back. He's 18 and easy to manipulate. This guy is 31. I forgot to mention the guys age in my original post. I feel like he's gonna get manipulated into going back