Tough situation. I think it really depends on what the incident was that caused Josh and Mark to be so opposed to each other. The incident may have been so vile that Josh is still affected by it if you keep talking with Mark, as that may show that you condone the vile incident or at least forgive Mark for it, whereas Josh obviously doesn’t feel that way. In general I tend to answer these types of questions with “live your own life”, as in Josh should not have a say in who you communicate with. This instance is different though due to the weighted backstory. I can’t say any of your two possible options (not talking with Mark, or talking with Mark) work here. I don’t think you should cut Mark out of your life altogether, but I don’t believe it’s fair to Josh to keep rubbing it in his face (I know you’re not doing that, but he may see it as that) and if Josh doesn’t want Mark in his life he is entitled to have that. Thus my final recommendation is to develop a compromise where Mark is not a part of “our lives”, but to not cut Mark totally out of your life. Talk with Mark only when Josh is not in hearing range, or better yet go out for coffee together so that Mark is not “infiltrating” your house via phone calls. Or communicate via email. Despite what Josh says, Mark IS your ex and you are entitled to continue your relationship in whatever way you deem fit. I understand that Josh had a bad relationship with Mark, but that does not give him the right to say “I don’t want him involved in our lives” – who is he to make decisions about the life the two of you have without considering your feelings and your point of view (in fact, while dismissing your feelings as he has done)? But Josh does have the right to have Mark not be in his life, just as much as you have the right to have Mark in your life. Despite your best efforts though, Josh may simply find that Mark’s presence is enough to cause him ire, in which case you will need to make a decision about where to go from there.