Why am I crying?

I’m sat here just watching tv on my own, the kids are in bed and out of nowhere I just felt this overwhelming feeling of loneliness. I’m actually breaking my heart rn the tears are streaming down my face. Wishing things were different, wishing my ex didn’t leave me and find someone else, wishing he wasn’t abusive towards me. Why am I crying over someone who hurt me beyond belief in so many ways imaginable? I haven’t missed him or cried over him for weeks so why now? I’m generally a strong person and have been through a lot. But even I have my limits and I hate this feeling! I just want my happy ending