could i have become pregnant from precum?

Well I am 24 weeks pregnant and before this, for about 3 weeks, I had cheated on my boyfriend with another guy. I confronted him about it and he knew why I did it and forgave me. He knows about what I am going to ask on here and doesn't really mind because he is still willing to take responsibility for this baby, but I need to know even though he doesn't mind.

Well My last period was on march 24th 2009 and my ovualtion date was supposed to be on april 10th. Me and my boyfriend had sex on April 9th at around 4 in the morning. He ejaculated inside me completely. The next night though, around 12 midnight, me and the other guy I had been dating were out and doing our own thing. One thing led to another and we had sex. I stopped about 15 minutes after because I felt really bad about what I was doing. I didnt let him finish at all, so he didnt ejaculate at anytime. I am worried about the 'potential' precum getting me pregnant although I strongly believe that its my boyfriend who got me pregnant because he fully ejaculated inside me and we had sex before I had with the other guy. What are the chances of this baby being my boyfriend's rather than the other guys?

Also, just to make sure who the babys father is, we decided to take a paternity test, but for now I just want to see what the approximated outcome is?