I Found Out I Was Pregnant 2 Days Ago. And

I found out I was pregnant 2 days ago. And I was supposed to start my period on the 7th, and my last start date of my last period was July 10th. I had sex with an ex boyfriend the 25th (I just found out my IUD was out of place and I didn't use any alternative protection) and I got back together with my current boyfriend the 29th, we had unprotected sex that morning then the next 4 days straight at least twice a day. I don't know who the father is now, help. It will decide whether or not I get an abortion. Extremely delicate and complicated situation. Please help.