help please

i am having a hard time dealing with stress and anxiety right now. I am dating a girl as well as other guys also (long story short, i'd love to be in a relationship with only her - but she doesn't want to commit.) so i have started dating around to both try and meet new people and get over her. my "girlfriend" is also my ex. we've gone back and forth many times. bad break ups and a terrible last few months. We have been getting along great *except the last two days* and tonight, her "boyfriend" (one of the guys she is dating) is driving in and coming to stay with her for two nights. I am having such a hard time dealing with that. she knows how i feel. she knows im upset. i can't stop thinking about them hooking up/sleeping together. the dates i've been on have been strictly kissing - if even. no sleeping together (not talking about sex, just in the same bed) she has asked me to save valentines day for her because she wants to take me on a date. i just do not know how to feel at peace with these feelings of stress, anxiety as they are together. i know as soon as he leaves, she will come back to me - i think. but having to spend my time thinking and worrying about it all is really taking a toll on my focus in school and such.

yes, i have been dating also - but for other reasons, including one to get over her. i do not sleep with them, have them over, etc. she calls me her girlfriend sometimes and then says we're nothing. i was supposed to be fine with this (she thinks) because im also dating other people - but i don't think its the same at all. i try and talk to her about it and she's tired of the same conversation.

i don't really know what to do or how to feel...

Maybe you can ask yourself if you feel comfortable with having been part of things becoming as they are.Ask yourself whether you feel this situation is the way you want to live your life.If it could be different ,,,,from the start what would you change?Maybe the relationship has taken too many wrong turns in the big picture,to salvage.It only complicates things to conduct relationships with more than one person intimately,jmo.Unless people are clear;from the start,that this is the way it will be.Sounds like there is hurt,and miscommunication.Whether one has been only snuggly and kissing and the other is pushing it into the wall...(lol)...makes no dif.The thing is both of you chose to be non committal and these are the results of the actions.I am no one to judge.So,I feel absolutely no judgement...but you need to examine what you really want,and find it.It may not be with this person,idk.I guess that time is of the essence as far as focusing on what you intend to do when and if she does decide to pursue you again.Hmmm....the impact on my studies,the stress on my mind and body....find your values and priorities according to your best interest...and stick to what you decide even if it isn't easy.Relationships can be intensely complicated...to be sure.