Baby by another guy????!?!?

Here's the deal. I was with my ex for 8 months when we split. We always used protection. Then in december, i had a breakdown and threw our life away. I ran into the arms of a pot smoking 25 year old from my job. And things were fun, there was talk of a relationship. We had all the time, We seemed inseparable, then on new years i made out with his friend, hurled, ped out and made a complete idiot of myself. He kicked me to the curb, and we didnt speak for a month. He finally text me one day after we ran into each other. And we continued to have . Last month, he came in me, ONCE but my period showed up. This month he did 3 times different days after my period. And my ex and i who have been hanging out ALOT since beginning of Feb, want to get back together possibly. But i have feelings for the other guy, and my ex. But the other guy, tonight, text me, then when he found out which friend i was with, he text her, saying shes very hot, etc etc. We both text him that he was being a , and he didnt reply to either. So im nervous. Maybe a smidge chance i got pregnant by him. No way in hell would he be there. How would i tell my ex? My period is due April 3. Is there remotely a chance for pregnancy? Please Help. Thanks!