D.I.D. Relationships

I just need a place to spill it all out before I go to bed and feel numb the next morning. I don't want to forget how much this matters to me. For an overview, my boyfriend has diagnosed did as well as sexual trauma. I am in a relationship with him and an alter. Recently, this alter got with another alter in the heads headspace (fucked around) and the alter I'm in a relationship caught feelings. Now, i haven't seen this alter in forever even though I'm dating him because he's had no motivation to front and I've been having fun with the host (my main partner). I can do anything with host because of their sexual trauma, I'm a very hypersexual person. Since the relationship started, I've thrown away any form of sexual intimacy with another person, even them, cause I don't want to chance scaring them. I feel hurt, frustrated, and so pent up that idk what to do. Mind you, this alter and I can't do anything either because the host would feel uncomfortable using their body to do such a thing. I'm so frustrated that my partner can fool around with someone in headspace because it doesn't involve the hosts body, but I can't do anything with either of them. Maybe this is morally wrong, I don't know, I just feel so mad I wanna sob and throw things. I've tried so hard to cater to their feelings, and they're just gonna come apologize "oopsie" that they fucked someone else, even if it was headspace??? God, what happened to my efforts???

No TLDR because I can't figure out how to sum this up. If anyone read through the whole thing, thank you. Give me our opinion.