Having affair with two girls those are sisters - what to do ?

Hi,

This may not sound good but I am in relationship with two girls those are real sisters. And now I am very much confused what to do ?

Here is my story in short, I met a girl , both fell in love with each other instantly, for a month or so everything was good but then found she is still in relationship with her EX. Meanwhile met her sister as friend, she is prettier than her older sister (my gf). She also likes me and eventually I fell for her. Broke up with my girlfriend as she confessed cheating on me with her EX but she said won't to again. Although I ended everything with my gf, she still says she may have had affairs in past but I am the person she only loved in real. Now in relationship with her sister and I can really feel love from both side and I think its first time I felt the love this way. But my ex gf (the older sister) still wants me in her life, even if there is no relationship and I find it hard to resist and that's where I need help. I tried very hard to cut off from older sister(old gf) but she just won't let me do. I feel now guilty because I don't want to do same what she did to me. I even told old GF that I am in now new relationship but she said she is ok with now.

I don't understand what to do, I do care about her (the old gf who happens to be older sister) and she is trying hard not to let me go. I already feel guilty to fall in love with her younger sister and she clearly know that don't have feeling of love for her (this older sister) and she is even OK with it.

I feel guilty everyday even I talk to my ex (older sister) on phone. She says she don't want anything from me and but she loves me.

I feel very tensed, sometimes I feel to stop all relationships (even with younger sister whom I really love).