AIO my girlfriend cheated on me

hey, i am just going through a really rough rough time me (20m) and my girlfriend (19f) have been together for 3 years on the 12th this month. On the 4th yesterday, my little brother (18m) came into my room and showed me a picture of my girlfriend on tinder who created an account im not sure when, i got really really upset and went to her house n broke up with her , i showed her the picture and she said "ok" n i told her parents who were in the living room at the time, then walked out the house and went home and blocked her number, i cant really give more information right now as i am having a hard time typing this out as is, i really miss her, but i really feel betrayed and hurt so bad i just can't do this

any help would be great n also i would love to talk to anyone i feel very alone right now