Needing some advice

So me and this girl had been bestfriends since we were little, we did absolutely everything together. It was like if you seen her you seen me and vise verse but one day I got a boyfriend and we were together for about 5 months than we started having arguments but we were still together just trying to work things out and make us actually work until I found out that my bestfriend had sex with my boyfriend!!!!! After that I asked them both about it and my boyfriend told me the truth and showed me the messages from him and her and all the nude pictures she sent him but she decided to lie to me, that just pissed me off even more than I already was. I ended up breaking up with the guy. Me and the girl whom I thought would never in a million years do anything to hurt me quit being friends. Well about a month ago she apologized and told me she’d never do it again and Im not gonna lie I did miss her because we went from being with each other everyday to never talking so I told her I forgave her but I didn’t trust her and it would take me a while to ever trust her again she told me that she understood. After that she started trying to hang out with me and I’d push her away because I didn’t wanna get too comfortable with her again but today we hung out and i don’t know if I made a mistake for actually giving her another chance. I really just don’t know if I should trust her again or not I just need some good advice because growing up I was always taught to forgive and forget but it’s honestly so hard to do! should I forgive her and be her friend again or should I just say screw it?