Broke up after 10 years (since 16) completely lost now

Hi, sorry not really don’t this before. In February me (26m) my ex girlfriend (26f) broke up, we were together for 10 years and had been together since we were 16. She broke up with me after we had a massive argument, like we’d never had before, and we both said some really horrible things, but I said worse things. I don’t blame her at all for it, I’m not here to be nasty about her. It’s just really had as I planned to propose in August, but yeah. She went to her family to tell them what I had said, and I didn’t go to anyone to say what I said.
We were texting and seeing eachother on and off up until like 3 weeks ago. I have been asking for space the entire time while she has wanted me to come over and be together and stuff, but I at the same time think, I can never rebuild the relationship with your family now, her little brother saw me as a brother and I watched him grow up and it’s all kinda destroyed now, it sucks tbh.
She didn’t want space, she just wanted things to go back to how they were. I felt terrible because I truly believe what we both needed was some real space apart to mature and grow in ourselves, but we couldn’t do that.

So a week ago I had to tell her, like we cannot respect the boundaries we are trying to set, so we have to actually just call it properly off officially.

She didnt take it well and told me she was sleeping with some rugby players in the weekend and then blocked me on everything. It kinda broke me because we were the only ones we’ve been together and each others first everything.

Sorry if this is long, not really sure what I’m doing