childrens father wants to claim son *income tax*

I just need to vent/some advice. This might be long.

Back in June of 2019(Father’s Day to be exact) I FINALLY left my children’s father. We have 2 kids together. 1 1/2 yo & 2 1/2 yo. He lost his job about 2 months before that. We were able to pay rent & bills with left over income tax money from February. When I first left him, we were on somewhat good terms. We planned to split the income tax(he claims one kid, I claim the other). But that was contingent on if he helped out with the kids financially. Since I’ve left him, he’s only seen the kids maybe 1-2 times a month for like 3-4 hours. he doesn’t even come pick them up, I have to take them to him. He basically puts no effort into seeing them. He pays absolutely NO child support. & only buys diapers like once a month. He says he works a lot of overtime, which is why he can’t see them much. I know that’s not true because when I’m being nice to him he suddenly has all this time off, mainly cus he wants to see me, not the kids. It’s ridiculous. Anyways, I’ve told him he’s not claiming either kid. He wants the income tax money so he can buy a new car & get his license fixed & basically all this shit for HIM. But I feel like if you’re not paying any child support & you’ve worked all this overtime, how do you not have money for that shit already? Lol I mean, I know for a fact he won’t be paying child support any time soon,so I believe I should keep the money for the kids. I just don’t know if I’m doing the right thing. Or if I should give him some money, not all of it?