Trying to stop worrying about my babys dad!?? Help!?

I am 20years old was with my boyfriend for 5years. I am pregnant now and due 2moro 27th march 2011. I remember having a period in may do not recall what day it started but i know i had it around 26/27 may as i was in ibiza then, didnt sleep with anyone. I slept with my boyfriend all through june using no protection and him inside me pretty much all the time. I dont recall the last date we slept together but was the end of june or beginning of july. I then slept with a guy friend on july 9th with no protection. I dont recall dates of period in june or if i even had a period in june. I was so scared to tell anyone i was pregnant being so young and not being in a relationship so i hid it. I had a scan on 21st dec and they said i was 26week and 2days and in january i was given 27th march as my due date. who do u think the father is? my ex has been fab and we are arranging dna but the guy who was my friend wants nothing to do with him/her. Im stressing about it and i know its not good for baby. Can anyone give me some advice please!! xx