Worlds are colliding

My worlds are colliding. I have many different groups of friends and I can't seem to work it out where the boundaries are not crossed. I don't know if anyone else knows what I am talking about. But I have lost a few friends to other friends. I feel that I have to keep some of my friends apart out of fear of losing them. I never used to feel this way, I used to think the more the merrier....I'm not sure when or what happened to change this? But the fact of the matter is I find myself lying and making up stories so one friend of mine can't hang out with another of mine. I fear them getting to close and leaving me out. How totally selfish is that!!! Maybe it was when my boyfriend and I of 5 years spilt...and I lost a lot of friends and that hurt and I'm scared of having that happen again.