My girlfriend and I are going to break up in 4 weeks and I don’t know what to do

My girlfriend and I (both 18) of 1.5 years are going to be graduating at the end of this month. We go to a boarding school, so all of the time we spend together is during the school year, we live 8 hours away from each other when we are not at school. We had already talked about what was going to happen when we go to college before now, and we both agreed we would probably have to split. We both hate long distance (which we have experienced all to much of with Covid, basically half of last year we spent apart) and we both know the benefits of breaking up probably outweigh the sadness.

But man am I sad. We are both so sad. I just spent the last hour crying. She was crying yesterday about it. We are so close, I spend probably at least 2 hours every day with her, we are both extremely comfortable around each other, our parents know each other and are friends, her parents like me, my parents like her. We have worked through all of the real problems that we had in our relationship, and we are happy. But now it is all coming to an end.

Unfortunately, I have no idea what mutual breakups are like. I know if people break up on poor terms, they simply don’t talk to each other anymore. But this breakup is completely mutual as much as we don’t want to do it. Should I just completely cut myself off from her? Is that what people do when they mutually break up? Should I keep in contact every once and a while? Do I delete all the pictures of us? Throw away the cards she made me? Completely erase her from my life?

Just for context, we are going to be very very far away from each other when we are in college, so if anyone was wondering, no, we would not be able to see each other during the school year at all. The most we would see each other is over the summer but as I said above, we live far away from each other so I basically would never see her.

I love her more than she knows, I just don’t know what is best for us after we split, any help/advice would be appreciated.

TLDR: Me and GF are mutually breaking up in a month, should I keep in contact w her or cut her out of my life completely? And if completely cutting her off is the best way forward, what is the best way to start preparing for a breakup to suppress the pain a bit?