How to deal with a hoe?

He wanted a baby and now I'm about to have one soon. This is our first child & we love eachother. We are only 18 and I'm 7 months pregnant. I'm now single bc he's always texting girls & flirting with them. And always on Instagram trying to text/talk to new ones. I know the answer is leave and I left. But I don't want to lose him. And I hate this it's making me want to break down. What do I do ? 😭