How will I know if he really loves me? Or if he's trying to destroy me?

When I began in school last summer, I was an outsider and this guy named Andrew, who was an insider seemed to develop an interest in me and I was pretty sure he had feelings for me but then he started hanging out with another girl named Katherine, who was my enemy. I was pretty sure they have become a secret couple when Andrew started talking with me again but every time we hang out he looks at Katherine like she have manipulated him into hurting me and suddenly me and Andrew hugged in front of her like best friends and then he doesn't show up for weeks. I was worried and did the only thing I could think off... Asking Katherine, she was surprisingly calm so I was sure that Andrine was real but when he returned he started getting a little mean, careless and revengeful, I was sure that it was Katherine's plan to destroy me.
It became the Christmas holidays and I searched on Facebook and found a picture of Katherine kissing another girl, which now made my theory die and when we all three returned to school again, Andrew said that he was attracted to the actor Chase Crawford. It made me really confused because he has seemed revengeful for so long and still does a bit.

Is he really gay or out to destroy me or is the truth that he loves me?