Lesbian relationship trouble :( help please :(?

hello, thankyou to anyone who has helped me answer this.

basically, ill try and keep this as short and sharp as possible. im 17 and bisexual, i met a girl who is 18 and for about 8/9 months we talked, fell in love and then went into a relationship after around 5/6 months. its the real deal, real love, we would talk to each other all day texting, then have 5/6 hour phone calls at night until 3 in the morning. we both went to college and it was stupid cause we would always be so tired but it was always worth it. we kind of began to become obsessed with each other, we knew each other so well and i was just so crazy about her.shes a very attractive girl and gets so much attention, shes beautiful, im not just saying it because i love her, but she is. and i got jealous so very easily even though she didnt flirt back. things started to change and i felt less for her, infact no. i felt less towards the relationship, i started going into town more and going out late and getting with people now and again. i didnt think anything of it at the time but would feel sick with regret the next morning. i only told her once that i got with someone but she took me back. shes not my first love, my first love was with a boy and god that was so amazing lasting 2 years on and off, but hes never left my mind because i love him still, but im not in love with him. does that make sense? like i thought all spark had gone between us. a group of us went into town one night and he came back to mine with about 8 other people, i was so drunk and we slept together. it hurts now to say it cause it hurts what i did to my girlfriend. i didnt even tell her im that horrible. she found out yesterday and ended it. it hurts but it doesnt hurt as much as it did with my first boyfriend. i love my ex girlfriend, its just different to my ex boyfriend. i dont want it to be over, yet i want to be single cause i dont want to make the mistake of it happening again. i cant stand to think of her with someone else. it makes me sick to my stomach. she said she needs space and things might not be over forever. i went round hers today and we just sat crying all night and day to each other. im such a cruel person. i wouldnt do it again. i just dont know what i want. i dont know.

im sorry for such the essay :(

my ex boyfriend has now gone to uni so it would never happen again, i wouldnt allow it. i just didnt follow my heart and went with my heart. ive told my ex girlfriend i will wait for her, i mean it i will, i will wait months. its just she is going to uni next year and i planned to as well. i previously wanted to take a gap year but things with me and her changed my mind..what do i do? im just so confused :( i know im horrible and untrustworthy and dont deserve her. im feeling so much pain and theres so much more left i know. like i dont want sympathy, i dont deserve it. i just want some honest answers.

thankyou anyone and everyone. x