My Gf 19F and i 18M are in a ldr relationship and idk what to do.

Hi, how is everyone? hope you all are doing well. Me and My girlfriend have been together for 3 Years and i genuinely don’t know what to do. We recently argued last year december because of what was happening between us and how LDR had became a difficult thing for the both of us. Especially the betrayal i had to go through. Now living with that trauma haha. Recently she’s been so busy studying and i sometimes feel guilty that i want to have some of her time. Everyday it’s just dry texts or no texts at all and im a overthinker which is bad ik. There are times i try to open up but get pushed away as if it doesn’t matter or she doesn’t have the time for it. Everyday she hangs out with this specific guy and i feel really uncomfortable. Because that’s what happened on dec. Now idk how do i handle this situation. Do i tell her to back off? but i dont wanna seem controlling. Or perhaps block the guy? they’re classmates and are in the same friend group. So how would i handle this situation?