How do you break up with someone you love?

I'm so tired... I tried everything, but a relationship won't work if only one person works for it. I'm just so done. I wanted my son to have a dad, but I'm hurting so much. Things have been shit for like a year now, how much time do I give him?? How much longer should I keep trying?? Our 4 years together, doesn't mean anything to him it seems...

Edit: I have suggested counseling to him, he said he'd "rather die than go to therapy".