Unsure

Me and my ex broke up about two weeks ago but agreed to stay on good terms. Im not sure if thats the right thing to do. Since we broke up he has been talking to two girls at the same time. Those two girls found out about each other and cut him off. About 3 days ago he began talking to a girl he used to talk to before me and him got together. He tells her he wants to be with her and everything but still calls me every night, texts me all day, tell me he loves me, and hugs me and gives me a kiss on the cheek when he leaves me. He tells me itd never change between us and he has my name tattooed and his hand and he says he wouldnt cover it no matter what. He has no idea I even know about all the girls. If I try to mention it he quickly denies it and just tries to say its them. Today my Nina passed away which he had met more than a few times. He told the girl he is currently talking to that HIS NINA passed away and was saying how close he was to her. I told my friend and she told the girl, she got upset and told him and he just ignored it saying whatever. I dont know if I should forgive I think that was really messed up for him to do considering I cried on the phone with him when I found out and as soon as I hang up he tells her otherwise. Im still not even over the breakup. At this point I dont know what to do.