Well, in your case i believe you should ask yourself ... have you just converted to a muslim for the sake of your ex-bf or because you really understand and feel Islam in your mind and heart ? because u must be very clear with yourself now, if you are a real muslim and believe in God from your mind and heart then forget about your ex-bf and just continue your life as being proud to be a muslim and in such case ( i mean by Islam regulations ) a muslim lady should only get married to a muslim man in order to have their kids muslims too ... u know if u married a christian man then your kids will become christians also as their father. While a Muslim man can marry from any religion in order to have his kids muslims too as their father's religion.
Hope this might help you a little bit in making up your mind angel.