Did 10 years and did exactly the same thing, he left got another girl pregnant, even though we had 6 kids between us, and I still chased after him for a year trying to 'fix' things.
All I can tell you is after he had been gone about 6 months I literally woke up one day and realised I didn't love this guy I was chasing.
It was the guy I had met I was in love with, and this person he had turned into was not who I loved or what I wanted.
But it took a while to separate the 2. To realise he was never gonna be the person he used to be.

I wish you all the best.