Relationship advice ?

I can't seem to get over an ex after almost 4years and now after all this time I feel like I love him and that's something I never told him now he is on and off in a relationship with the mother of his child and I just recently ended a relationship with the farther of my child now I can't seem to get him off my mind I want to write him but idk if he still feel the same way after all theses years

PLEASE SOMEONE GIVE ME SOME ADVICE