my girlfriend [23F] got raped and i [26M] feel betrayed

first off, this is my first ever written english so be patient with my spelling.

so 3 month ago i (26M) found out alot of different things about my gf (23F). we have been together for 4 years and i really love this woman, but. over these 4 years she have been away on 3 stays at school, between her interships here by our home. every stay at school have been 5 month and she have been home every second weekend. we talked alot about the guys trying to hit her up, wich helped me build trust in her during these stays.

first school Stay 3,5 years ago. we dont call ourself boy/girlfriend, but she does go to my place and stay every 2 weekend when she is home. she tells about a few boys, but I just found out she did sleep with 2 guys a few times, she even did the deed with one of them 1 time. after she did finish this school stay we became official a couple and she soon moved in with me.

second school stay 2,5 year ago. to my knowledge nothing happened here in that sense, tho she felt a bit lonely over there some days.

third school stay 9 month ago. here she had a few boys trying to get her wich we talked about and made a bit if fun with texting them after she had told them about me. but one guy got held a secret to me, this guy was very offensive on getting to her and she replied just as nasty as he wrote her. 3 weeks into their texting she had her first anxiety attack in 5 years one night around 0200. she rushed to his room wich is were the whole class always stayed after school. at this time he is alone in the room and he grabs her and comforts her. 10 min into this he drags her over to the bed and pull off her pants and do his thing while she cries. This is 1 month into the stay at school and throughout the rest of the school stay, he came to sleep and .... in her bed every night. he did it in all thinkable ways to her.

she did ask him to come down sometimes, they talked on phone, texted and just had contact all the time. she have been very afraid of him through this 6 month and have done every little thing he asked of her, like driving when he was drunk etc.

i have seen enough evidence, that i have no doubt no more that this was rape. she have been to the police and is getting help to manage her mental trauma too.

i found out about everything myself, through rumors and lurking around. she did lie alot in the beginning, but as i got more evidence she finally came clean on everything that happened and helped me fill in the gaps in my story, even the ones who made her look bad. this was in short terms all the bad stuff happening in our relationship the past years.

but here i am now, i want to support this woman i love so much, but navigate through this is alot right now. i was betrayed and manipulated. havent decided anything yet, I have to turn everything around in my head a few times first, but staying with her sadly looks dificult.

besides all this i am the only stable thing in her life as her mother never have been there for her and her father is very ill right now. how do i help her the best way possible if i lileæy choose to walk away and what are you thoughts of this insanity???