Iv been havin dreams about me and my bf breaking up :( what does this mean?

I used to dream about us getting married and everything. but lately EVERY TIME i go to sleep i dream about him leaveing me and me seein other girls all over him.. i know there just dreams but it still hurts i woke up cryin ther other night.. and and i recently found out i was pregnant and we dont know if its his or the guys that d me:( am i affraid he will leave me if its not his?...and for those who care...the guy is serving his sentence....