your opinion

So, I'm 10.5 weeks pregnant. 
My last menstrual cycle was 2/8/17. 
I had sex with my ex about every other day or every other couple days. I had sex as well with a guy that I was talking to at the time on 2/22. I'm searching for opinions on whether it could be my ex or the other guy. 
My ex doesn't have any kids. And the other guy has two. 
They both know, and my ex is stepping up. Opinions? Please don't judge, I've had a lot of that here recently