Newly diagnosed

I haven’t been officially diagnosed but I’m 99% sure just from my symptoms and the looks of things. It’s been really rough, it just popped up Wednesday. I’m only 18 and I’ve only ever slept with one man, and he was someone that i trusted so much. We were also together for about a year and i never had any issues. Over the summer he left and we ended up breaking up, i guess that’s when he decided to sleep with this one girl. I just don’t understand why this would happen to me, and I’m devastated. I wish i could go back in time and have never taken him back when he came back home after summer. There’s so much i would’ve done differently. People keep saying it’s not that bad but honestly to me it is that bad, and i am sososo depressed. I feel like my entire life has been flipped around and i don’t know how to cope with this. This may seem overdramatic but last night i just really wanted to die. I’ve been crying almost nonstop & it’s very hard for me to leave my room. Does anyone have any good tips on coping with this?? Especially when you’re in college and have stuff you need to get done, but just can’t ?