How can i get over her?

Me and my ex are both 17, however we will both be 18 at the end of this year. I loved her so much and thought that she felt the same. I know i sound like a whiny little child, but i was always the weedy kid that everyone picked on in High School. To the extent that i felt there was something seriously wrong with me. She was furthermore the first and only girl who came into my life during the past year and as cheesy as it sounds made me believe in myself again. As of late she started seeing me less and less (we became a couple last Feb) and rumors were spreading that she was doing some stuff with other guys. When i asked her about this she would start crying really hard and saying that she loved me so much and that she would never do anything to hurt me. I believed this until i got into a fight with the more popular guys at School and he told me that she had been lying to me and that she had it real bad for him. When i called him the liar, he showed me the sexts that she had sent both him and his friend (they were very very recent) and very recent pictures of her naked with the main guy. When i finally did confront her (in front of half the year no less) she got all defensive and said that i was a loser and that she only ever went out with me because i was a poor substitute for the guy i had a fight with/she slept with. I said (through tears) that i had been played the whole time and that i actually believed that she loved me. Now that what happened between us has spread, the rest of the year has tormented me more so than average. Even now i find it hard to accept that all those kisses and makeout sessions were a just lie, i also feel as though i'll never be loved by another girl again and that there possibly might be something mentally or otherwise wrong with me. Recently she texted me saying she was sorry, she was just drunk and that she truly wants to be with me.