The biggest mistake i have ever done

hello im 16 to 17 years old and a high school student.Last summer i started to chat with a girl a friend met to me and both of us wanted to chat to each other the whole day.after 2 weeks we finally met each other face to face.It wasnt something special because it was her her best friend her brother and my best friend.we hung out to his house the whole afternoon till midnight cause she had to leave.After this day realised that she liked me.so i told to my best friend to find out if its true.he asked her best friend and she said that she likes me.When i learned that she wanted something more i got stressed because i dont know how to handle this situation.Well 2 weeks before christams this year a friend invited her to his party and i thought it was my day but the guy that was doing the party told me that he likes her too.i didnt want to continue the convertation and i left.i didnt want to betray my friend so i didnt want him to know that i like her too.when this girl came to the party we said hi to each other and after an hour we started talking again.i was a bit drunk and i thought noow its the time to kiss her.i told her to go for a walk and she said ok .when we left the house i was ready to kiss her but my friend appeared and saw us together outside.he told me to get in and i followed him cause i was drunk.the day after the party me and my friend argued we dont talk anymore.then i told her how the situation is and she said that he doent like him cause he doesnt have a good personality.anyway after all this i was like i dont want to talk to her anymore cause i was sad with all this situation.but 1 month after we started to talk again for hours on facebook.we didnt have any mutual friends and it was very dificult to me to meet her somewhere.so i had the option only from facebook or snapchat.so a friend that organized a party and cause they became friends too he invited her.I wasnt that comfortable because we have met after the previous disaster only some times for a while.but i was sure i could kiss her.But it was the worst thing ever happened to me!me and some friends got drunk to do shitty thing and have fun and i forgot about her a lilttle bit.when we said hi to each other i said i wanted to talk to her at the start of the conversation everthing was perfect i kissed her a lot of times in her cheeks and i was really happy but again her ****ing bastard brother he is 1 year younger
and very anoying i couldnt talk to her i went back to the party and i got drunk very bad.then i told her a lot of things that never had to know and that i love her.i learned about all this the next day cause i didnt remember nothing.i felt to bad i
wanted to suicide.i still repentance this day.after this i realised that she changed the way she talks to me .its like she talks to just a good friend nothing more.and i really dont know how to make her feel like before the PARTY.The friend that organized the party talked to her yestarday and told to him that she doenst feel something about me and she wants to find a boyfriend because she had no boyfriends from the day we started to talk.PLEASE SOMEONE HELP ME I DONT KNOW WHAT TO DO