Pregnant by My Ex

The title explains it all. My ex boyfriend, in which I've been dating for a year, and I broke up about 3 weeks ago. He had said he needed some space, he needed to work on himself, its not you it's me, I still love you blah blah blah. Which stupidly in love I believed until not even a week after the break up he had started seeing someone else. This someone else has happened to come up before in our relationship when we were on a break. They've been very public about one another, and apparently he's been with her everyday since. Anyways enough about that, the root of the problem is I found out this past weekend that I'm pregnant. And it's by him. It's so ironic that I've never gotten pregnant in our entirety of our relationship and all of a sudden, a baby is here. Also coincidentally when I found out my ex texted me asking for his stuff back. I hadn't heard from him since my birthday which was two weeks ago, but it was only short conversation. I've been implementing this no contact rule thing so I didn't automatically text back, because I wasn't sure if I should tell him or not considering the rule. I ended up replying a couple days later agreeing to meet up and that I had something important to talk to him about. Well now the day is finally coming and I'm struck with panic and anxiety because I'm unsure of how to tell him, I have the pregnancy tests and ultrasound to prove it. I'm afraid that he would respond negatively, and that he'd want me to abort it or not be involved or worse not believe me, or that it's his. I am accepting if he doesn't want to be involved, and that he is entitled to his opinion and I am keeping the baby. But I'm wondering should I really tell him? I know it's his and I know I'm capable of taking care of this child. How should I approach this?????