My ex wants me to have sex with another man now that we are broken up

My ex always liked to hear about me telling actual or made up stories about my previous lovers especially my ex before him. I thought it was weird but I have to admit I enjoyed it because of how much it turned him on. We didn't do this all of time. We usually had sex "just us" and no stories. Now we are broken up. It has nothing to do with that topic. We have been broken up for a month. I hope he still loves me but he says he don't but it came up by my idea to be fwb. btw we have a baby together. Anyway he told me he didn't know because he would want to take his fantasies to far. I asked what he meant and he said what if I really want you to have sex with another man (something he told me before during sex but always said he really didn't want me too and if I ever did we would be over). I asked who and he said my ex before him mainly but anyone I wanted too. Fyi...I don't want to nor plan too. I asked him would it bother him and he said no. I don't know if he means it or not. Just recently he acted very jealous when my ex before him was brought up and always did when we were together as well except for "our pretend time". My question is...do you think my ex could really want me to have sex with my ex or another man and still be in love with me? Could he want me to do that and not get upset or jealous at all? I know it was all just fantasy before. I just don't what to think. I was hoping he still loved me and would realize it soon because we never fought a lot and our only big fight was dumb and he jumped the gun and moved but even told me wanted to work it out etc..then he said he didn't but I was pushing, and begging etc. Now I'm trying to be cool and just be friends because we have a child so want to get along. Plus he's my best friend and up until that dumb argument he told me daily he loved me. He told me i made him happier than any of his exes and he wanted to marry me one day. This break up came out of the blue. So could all his feeling be gone since he actually wants me to have sex with another man or was he testing me? Idk. Help...advice!