8 years might be over

Me and my SO have been together for 8 years. I dont want to marry him. I dont plan on spending my whole life with him. Im not happy. I know thats harsh. Im thinking about leaving but i dont want to ruin christmas or him. But i cant sacrifice my happiness anymore. I dont know how to tell him. Hes not going to understand. He thinks everything is fine. But its not.

Throigh out these 8 years i almost left him 3 times. He says he wants to marry me so i cant leave him. How "romantic". I almost left him for the way he treated me, for him not holding a job down, not only that but while i was doing everything to finacially aupport our family he couldnt be bothered to clean the house or cook me supper. I had enough. And know i realize that i just dont care anymore. I dont care if he cheats, i dont care that he spends every single night on fortnite, i dont care that he rarely sits down to eat supper with. But i do care that im not happy. Im not my happyself that i was years ago. This goofy girl that barely got bothered by anything. We have three kids together and debt thats under my name and i dont know what to do or how to go about it.