Girlfriend cheated on me what should i do Options

[chicubs88]

ok so last weekend my girlfriend went to a party. the thing is she never drinks and that night i guess she chose to. I wasnt invited to this party because it was her and her brothers friends party. so she decided to drink and i guess what happened is that she made out with some other guy that night. people took pictures and now i look like a bitch cause i got cheated on and so many people know about it or have seen it. she told me the next day because she and i cannot lie to each other about things like that so she just flat out told me. she said she didnt mean to do it but and she didnt know she did it. i know that that isnt true. i know that she knew she did it. but what hurt me the most is that she did do it. the rest of the weekend i did very stupid shit. (i was a former drug abuser till i met her and i quit) she made me feel so bad that i went back to what i used to do to cope with problems. Technically i should be dead for what i did that weekend. So i talked to her and she says she loves me still and i still love her but i cant trust her anymore. i feel like what we had didnt mean anything at all and that i was nothing to her. im not sure what do do now. is there any opinions on how i should handle this because i want to leave her but then again i dont. please help