Mono-Poly relationship, need advice
I apologize in advance if I ramble a bit.
I have been with my Fiance (I'll call him Abe for now) for 6 and half years. We came into the relationship knowing that I am not poly and he is. We have always agreed that when the opportunity arose for a poly relationship we would go slowly to make sure that I would be comfortable and assured that I wasn't just being replaced. He has had 5 different women that he has attempted to bring into the relationship. The first 4 failed miserably for various reasons. The 5th woman (I"ll call her K for now)is the current "attempt".
Abe and I moved to the South Bay Area back in April of this year for is new job. We started subletting half of a house from a co-workers friend. The person we are subletting from is K. About 2 months ago I had agreed that Abe and K could have a physical relationship but that I wasn't ready for them to start dating yet. To try to keep it short I'll just say that that ended badly within a couple of days. We all agreed that before it was attempted again that I would be informed and that they would do nothing without making sure I knew about it and was ok with it again. Took a couple weeks to settle back into being friends/roommates. I had been told by both of them that they didn't have any feelings for each other, other than as friends. Neither of them acted any other way than as friends.
Two weeks ago my mother passed away. It was rather unexpected and sudden. While I wasn't close with my mother most of the time, I did still love her as my mother and am still devastated with her loss as now I know I can never fix the relationship I had with her. K paid for the entire trip for me to be able to attend my mother's service. Three days ago, I am informed that Abe and K have serious feelings for each other and cannot control them any longer. I am also informed that they have already started exploring a physical relationship. While no intercourse has occurred there has been make-outs and heavy petting and gratification with hands. Needless to say I feel rather betrayed by both of them. However I am more able to forgive Abe as he has always told me that he couldn't promise he would never "cheat", but that he would try to follow the rules we had agreed to as much as possible. He says he got caught up in the heat of the moment with K and knows he messed up very badly. I, however, seem unable to forgive K. Part of that is that Abe did tell me what happened, a few day after, but he did tell me. K has yet to say a word about it.
Anyhow, after a long talk, I have agreed to just jump in and let them explore their feelings for each other, with understanding from both of them that, while unfair, I need more attention from them than they will be able to give each other as I'm still grieving over my mother. Yes, the timing couldn't be worse...
Abe has laid down a handful of baseline rules that I agree with, and I'm willing to try. My problem right now, is that I don't feel very rational or logical. I have never been able to lie to people, I tend to be honest to a fault without meaning to be. Abe has asked that I not confront K, or treat her any differently than I did before all of this came up again, because he doesn't want her hurt. K tends to react VERY badly when she is hurt. So now I feel like I'm lying to her because I'm acting like I'm ok with everything and that she hasn't caused me any pain. Any time I tell Abe that there are some things I'm not ok with him doing with her, he tells me I am being unfair to her.
So I guess long story short.... I'm willing to try to take this on, but at what point do I get to be "selfish" and be more worried about me and how I feel about something than be worried about if it will hurt K or ruin the chances of them being happy together? Being as we have never really gotten this far with any of the other 4 women, I'm at a loss as to what is normal to feel and what is ok to say or do and to whom and when. I just don't know... I'm hoping some one here has had some experience at least a little similar and can help me with advice on how they got through it.