Hi T-
First thing that popped into my head when reading your post is " lucky her" ( his girlfriend, I mean ).
Try not to beat yourself up about what you did or didn't not do sooner. You are no different than most of us here. We all have given 110% to a relationship where our partner was giving so much less. So, pick your chin up, be proud of yourself for giving it your all and more not only for yourself but for your child/children. YOU my dear deserve a life without the chaos let him call his new " girl", God help her, when he feels the need to say Goodbye.
And yes, I agree with Thomas up there^^^^. He is trying to manipulate you! My advise? Put him on block!
Good luck to you.... We are here!!