Do I tell him I'm pregnant??

This is going to be long, I'll try to condense it but please read and please give your input and advice.

My SO who is now recently my ex had to leave me because there is an issue with my age. I am significantly younger than him by 15 years. His ex wife and mother to his 2 kids found out that he started dating me before I was legally an adult. She threatened to call the cops and take his portion of the custody away from him if he continued to see me. So he left me and I understand so yeah it's ok.

Anyways. I'm pregnant and I only found out after we went our separate ways. Yes it's his because he's the only guy I've ever slept with. I can't bring myself to tell him. Please don't judge I care about him but I don't want to ruin his life by telling him he has another child on the way. I don't believe in abortion I am pro life so I'm planning on moving away and essentially hiding it from him and raising the baby on my own. I still plan on giving the baby his last name but I'm afraid that if he finds out or his ex finds out or if he comes and sees me to be with me and the baby it'll have negative consequences.

Please help.