Friend problems..Please help me im so...!!!?

Okay, so I have this best friend (ashlyn) and we have been good friends since we wherre very young. (like first grade) well things have always been great, untill this year when we where in 7th grade. She met a girl named Jesse, and they became friends. (and i was fine with this) Well, Jesse doesn't know how to make friends unless she can make them feel sorry for her. So ya ashlyn and Jesse had a sleep over, and Jesse told ashlyn all this **** like she gave a dude a bj on a church van, and she was cutting herself, and she tried to hang herself once. And i think that hooked ashlyn. She was scared. Jesse would call her or text her and tell her that she was going to kill herself. Ashlyn would FREAK. ( shes one of those really sweet nice kids thats really protected from all bad) she would call me scared asking me what to do. Her and Jesse would get into fights, and Jesse quickly wormed her way out by saying she was Going to kill herself, so ashlyn would be scared and take her back. So Ashlyn couldn't end their freindship, she didn't want the guilt of somebodys death on her shoulders, wich i completelly understand. Well, they started hanging out more and more and more. They became best friends. Jesse convinced ashlyn that i beat her. Ashlyn startd saying that i would hit her and all this crap wich i still dont understand (lol) well then Ashlyn started going back and forth beetween me and Jesse. SHe would get in a fight with me, go to Jesse, get in a fight with Jesse, go back to me. And finally i just stopped talking to her. altogether. It stayed that way for about 2 months. Then She started texting me, (why are you mad, what did i do..?) But i ignored her, i had other friends. Better friends. Friends that didnt come with pyhsicotic maniacs with them. But i started to break. I love ashlyn, shes so...just like me. We are honestly the most ANNOYING people ever when we are alone. I would stumble across old pictures and videos we had taken on my webcam and just start to cry. I no longer had a best friend, someone to tell everything too..and it sucked. Well, ashlyn and jesse got in another fight, and ashlyn appologized and everything before they even got in a fight so i took her back..and honestly, this is THE last time....... We haven't gotten in any fights since. Things are better then ever, and i am really happy. And ashlyn and jesse hadnt talked...untill now. THey have started IM'ing. Ashlyn promises that they wont be friends but i really dont trust her. I think they will. I KNOW they will, and i dont wanna deal with Jesse. Jesse will just come into our friendship and completely ruin it like she does everytime. AND me and ashlyn cant talk like best freinds like we normaly do because she will always tell jesse what i say. WELLL!!!!!!!!!!!! like 2 days ago i posted this question asking if i was overreacting that they where talking, and if i should worry if they where gonna be friends again. WELL I just saw on facebook where they where talking and loling and talking about old times. ANd i asked ashlyn and she said they where friends again. I AM SO FREAKIN MAD!!! she SWORE to me she would never be friends with her again. EVER!! and now here they are.. ANd i swore to myself that when i decided to give her one last chance that i would NEVER be freinds with her again if she was friends with jesse again. You dont even understand how upset i am, i am freakin cryin!!! i never cry over crap like this!!!!! I dont NOT wanna drop ashlyn again i cant..cus then her and jesse will become bffs and i will just go freakin crazy. Please somebody just tell me what i should do!!!