Guy's Behavior

What should I do this is destroying my mental health?

We went on a school trip for 3 days. In this trip was my old friendgroup too that was trying to make me feel bad about myself but i didn't care. In the room i was with 2 girls that were in that friendgroup. After clubbing the last day at night on the trip the 2 girls went on a room and all the friendgroup was doing a sleepover. After i wake up the 1 girl comes to me and asks me if i have seen my crush story on ig (the friendgroup knew who my crush is) and i said i can't see something he hasn't posted. Then she shows me a pic where he was hugging a girl (no showing faces) and i was confused cause my crush even if he had a gurlfriend he would never post it on ig. Then i showed it to my friends and we all said that it looks like my ex bestie. After learning it was her i became anrgy ( the whole friendgroup was planning to do this so i would get sad) when i went to the lobby all my old friendgroup started screeming "HOW DO U FEEL THAT UR NOT SINGLE ANYMORE" infront of me. Theyre not together they just did it on purpose so i get hurt. Now a friend of mine told me that he heard something. They all hang out for someones birthday and my crush was there. My old bestfriend was saying "hahahahahah i played the role so good bro but she didn't believe it she understood that it was me in the pic" and then my crush said "send her a message that we are together so she stops" my heart fell down to my stomach, cause he was in the plan too.. And i never did something bad to him i always tried to be nice with him. The old friendgroup told him that i like him and he said he doesn't and did all this but he always gives eye contacts always comr talk to me when the change is given always come close to me and many more. I can't understand. I broke into tears when i learnt what they did tho. What should i do?
What should I do this is destroying my mental health?
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