I can totally relate to how you are feeling. My "significant other" and I have dated for 2 1/2 years now. He is 19 years older than me, but our time together is normally wonderful. That is, until his daughters get involved. They are both in their twenties, are married with children of their own. This was a litte hard to get used to in the beginning, but the fact that he has grandchildren and I don't even have a child of my own was really just something to get used to. Overall, we are the best of friends and love each other deeply, and that is what matters. However, now it is all coming to an end because of a situation with his daughters. One lives 7 hours away and the other lives 2 hours away. They never came to see their dad until he and I bought a house together and things really began to get serious. Then, they began coming in more often, which I have never had a problem with. In fact, I had invited them to come and spend holidays with my family. We all wanted them to feel a part of our family. The problem is that they didn't want that. They said that since they don't see their dad often, when they come in for the holidays they expect him to give all of his attention to them. That means that I am not to even be around. They want his undivided attention, and if he says a word to me or holds my hand, then I am intruding on their time with him. So, as a result, when they come down for a holiday, I am not invited to spend it with him or them. He told me that the oldest walked out of his life for 2 years when she was a young girl because he sided with his spouse over her. Then when they divorced she came back to him. I understand his position, because his first son never had anything to do with him because the boys mother made sure there was no contact between them. So basically, his girls know that he would do anything for them just to keep from loosing them like he lost his son, and they emotionally blackmail him into getting what they want. He will never be able to have a relationship with anyone until he learns how to stand up to them and put a stop to them running his life. So, this Thanksgiving he is going to be with them and will not see me at all because I am not invited. In fact, his own father has cancer and is not doing well, yet he is going to see his daughters because they make him feel guilty if he doesn't. It's a sad situation. I just wish he could see what they do to him, and realize that when you love someone you want them to be happy , even if it means having to share his time and attention. Putting him in the middle of us only makes him miserable, that is why I decided to step aside.
I know you are hurting and confused as well. Know you are not alone!