Child support from narcissistic ex, now it's my fault

I put an order in for my narcissistic ex to pay child support for both our kids and now he has said to delete his number, he doesn't want to hear from me again and to "explain" to our kids what I have done so he doesn't get the blame . I have given this man so many chances to help provide for the kids and be there for them and each time he refused to help and refused to spend time with them, and when he did he literally argued for the money back the next day and spent a 2 hours a day every couple of weekends with them. He's paid $200 3 times in the last 9 months, and not a penny more since our 6 and 4 year old were born. But now that I've contacted child support, he's decided to have nothing to do with our kids and still has the audacity to blame me for it? This man has made my life a living hell, played so many toxic games, ran my name through the dirt with disgusting lies and rumours, tried to fill my kids minds with horrible things about me, and I can only imagine the things he's going to come up with now that I've asked for CS and him blaming me for his own decision making on his kids lives. How can something so normal, like providing for kids you made, turn into such a stressful effing situation.