This is the place to write those angry thoughts, so let it out. And in your sitch I wouldn't fault you for letting him have it. Although I wouldn't have even replied to the text at all. Sometimes saying nothing sends a better message.
I watched my SIL go through something similar to you but without the baby. She held everything in and she still let's him get to her. He has done the same things, like Mexico trips, while telling her he didn't have money to support his own children. It has been a few years for her. She moved on rather quickly and I don't think she has really dealt with what went wrong and is finding herself having R issues again.
I think it is great that are here, that we are all here to learn from this. Just remember you only can control yourself.
Me 37/W 32 S 5 D 4 ILYBNILWY 5/12 Sep 8/12 Starting to find myself 11/12 on