Inconsistent kids dad . WDID?

My children ( almost 7&9) have the most inconsistent father. Over the last 3 years I’ve told him our kids need consistency but he chooses to ignore them until he or his gf feel like having them for a few hours. In 2022 he last saw them in March, this year he has seen them once in Jan.

HE LIVES A 4 MINUTE WALK FROM OUR HOUSE. Each visit the kids leave with plans for the next visit, more often, then are hit with the excuses when asked to visit again. This usually happens for months on end (10 months longest) til he feels he wants them for the day again. His gf is no better and doesn’t understand they need consistency and helps the father blame me for everything 🤦🏻‍♀️ my oldest has since blocked her dad the only way they have contact (the Fortnite game) because she had enough of begging him for a visit. Anytime I say no I become the bitter baby mama keeping them from him, and the girlfriend will put it all over social media. So I’ve stopped saying no and letting him dig his own grave with excuses but it’s killing my kids each time he does it. How do I deal with this issue? Do I continue watching my kids get damaged by him, do I put a stop to it next time they ask and deal with their crap talking? What do I do? The girlfriend doesn’t allow him to contact me, only she can and she tries her hardest not to understand anything about my kids and their feelings. So I can’t exactly communicate and even if I could he is very very narcissistic. I just want to pack up and move away. I hate this