How do I respond to a Im sorry text from ex boyfriend ?

I really liked him a lot and we were together for 3 months. During that time I met his mother, lived with him half time. I guess the last month of the relationship he started getting attitudes with me and told me him and his ex were in contact because she lets him know when he gets mail. I stayed calm and didn’t over react. Even though lowkey I felt he wanted a reaction out of me to prove my love for him. Some men can be kinda toxic like that. Especially the men who say they hate drama, they hate fights, usually it’s the total opposite. So during arguments or if he was mean to me I would either get quiet, or cry because I’m kinda cry baby. I also was in a very mentally verbally and physically abusive marriage in the past so I said I’m the future I do not want a guy who yells at me. When he gets mad he is not the same. He never physically hurt me but he doesn’t know how to calm down, even when I show I don’t want to fight or argue it’s like something triggers him to want to win. So 3 weeks ago that same thing happened. I wiped my tears stood up and said it really hurts me to do this but I’m breaking up with you. The crazy part is I really liked him, we went on dates, I met his mom who I love, I let their pets, we were together everyday, to the point where I tried to get some space and he would insist that I come over. Not trying to take his side at all but he did come out of a breakup when he met me. I think he thought he was still in love with his ex. Then when I actually walked away he realised he loved me. Also I miss him and cried for him every other day. Yesterday he contact me to tell me I had some mail. I came by to pick it up, but I made sure to look very pretty I changed my hair and worse a pretty summer dress. He handed me my mail and he talked shortly about fixing his car, then I said thank you and hope you have a good day. While driving down the road I was holding back tears because I miss him. I also wondered if he miss me too. Then when I was laying down tossing and turning her randomly says he is sorry. Which I have not respond to yet because idk what to say and I’m scared if I respond it may be the wrong thing.