You forgave him, he did it again. You can forgive him again, he will do it again, because there are now no consequences.
You are young, you have already one child to look after, and they should be your priority. Can you cope with two? Can you afford two? How will being a single parent to two small children impact the first child? You have a job and a degree to complete, will you have to give up on these if you can't cope? You have thus far coped with one child, a job and a degree. More than most of us can cope with, so hats off to you.
For me, it would be a no brainer. I would kick this sorry specimen to the curb and I would probably book a termination. He has shown what sort of man he is, why wait to find out what a sorry excuse of a father he will be.
If you can't bare the thought of a termination, or you are unsure, you can get some counselling first to help clarify for you if it's the right thing.
As for him, I'd let him go meet his non existent date, then while he is out send a text saying "sorry I'm running late because I've packed up ex bfs stuff and left it at his mum's, signed catfish (whatever name you used)