GF and me broke up after 7 years of relationship

Hello, this is gonna be a long one.

My Gf and I broke up over our long term goals in our life. I grew up on a kinda farm and always told her that I see my future on the farm (not working as a farmer, but its the place I grew up on and it was always my plan to live there). I told her really early on, like 6 1/2 years ago, while she was never as exited for it as me, it never seemed to be a problem for her, she rides horse for a hobby and we had often talked about how we someday have the horse standing on the farm and maybe keep some chickens. My Gf was 19 when we got together (I was the only Partner she had in her adult live) and I was 23 when we got together, now she is 26 and I am 30.

Fast forward to like 6 months ago, we start to make plans for the house (we have to tear one down so we can build a new one). She starts to worry about how, now that it comes closer and closer, doesnt want to live on that farm.

3 Weeks ago she told me she cant imagine herself to be happy on the farm, I dont want to leave the farm behind, we couldnt find a compromise and broke up. We lived in a small apartment in a city. I decide to live at my parents on the farm and she keeps the apartment. We decide we want to try and stay friends, since theres no problem between us, only our life goals ( she dont really know what she wants in her future) I help her numerous times in the apartment, sell her my car for a very moderate price (condition was she does all the paperwork so I have time to move in with all my stuff at my parents but I do a last service on the car, because im a car mechanic, she offered to pay me but I declined). That all was 3 to 2 weeks ago. One week ago I hear rumors that she has a new guy, but you get easily paranoid about that stuff after a breakup, so I wait, but more and more details emerge.

Yesterday I confronted her, she admits everything, we both stay pretty calm but cry a lot, she says that this was a giant mistake, she swears there was nothing goin on when we were still together and I believe her on that.

Yesterday evening we wrote another, I wrote her how much she hurt me by hooking up with another guy after 2 weeks whe I tried to help her with the apartment and car and that I cannot see her again because Istill have feelings for her. She wrote me that she understands she fucked up big time and hates herself for hurting me but still loves me, how I always was her best friend and perfect partner for her and that she understands how dissapointed I am and that it was probably the bigges error she ever did.

Today in the morning she calls and asks if we can meet up and talk and I accept that. We talk and we finally talk about why we broke up in the first place, and both understand that we both misunderstood ourself in a lot of ways about living on the farm.

Now I would have easily taken her back if it was just that, but she slept with that guy only 2 weeks after we broke up and that really really hurt. I know she was hurt and desperate and confused about what she wanted, but damn, 2 weeks after 7 years relationship! You are an adult and your actions have consequences.

Some hours ago she asked if we can talk again on Monday, I said "Yes, we can, but you have to end whatever it is you have with that new guy, but even then, I dont know if I can forgive you"

What are you opinions here? I know I still have feelings for her, and I know she has feelings for me, but what she did was really shitty, especially when I helped her and behind my back she was probably already fucking her new guy.

I really dont know what to do, I mean, in my heart I want her back, but my brain remembers what she did to me.