Sisterly love....?

My boyfriend of three years and my sister used to 'date' before he and i got together. We have always had a very open relationship and a great sex life. He told me that he was 'bored' with our sex life and asked if my sister could join us. The sex they had together previously was very good and he really wanted to engage in a threesome with the two of us. (I should add that she isn't my biological sister, we simply grew up together in the same household. Our mothers were best friends and both single mothers and lived together and raised their children together.) Anyways, after alot of discussion between the three of us and my boyfriend and sister begging me, I agreed to it and we made all the necessary plans and arrangements, she needed a baby-sitter, I didn't want it to happen in my bed, etc.... Well I wasn't feeling well the night we had planned to do all of this and so told them they could still do whatever and asked that they stay home because I wasn't comfortable with them being in a hotel all night away from me, under the assumption that they knew to use the guest room. Well, they said it would be oral only and that they would be back 'soonish', I said, "whatever. Just don't be too loud and clean up after yourselves". Well, they ended up on my bed and it WAAAAYYY past the 'just oral' they had claimed. I feel like I shouldn't be mad at them because I did say "whatever..." but it really hurt me that my sister was the one that insitgated the penetration and that he ejaculated into her with NO protection. After 3 years, he won't even do that with me WITH protection. I just need some advice because I'm not sure how to feel right now...any advice or something similar happen to anyone?

Hi Sorry to hear that your sister and boyfriend didn't stick to the plan Sounds complicated Not sure u can tell you what to do I feel upset for you However I do enjoy threesomes I no longer see my best friend who I had one with I think you need to talk to your boyfriend and take your sexlife away from your sister May join a club Or find someone brother of you know Good luck It wil be hard but sooner you talk to your boyfriend the better