Are you going by what you have guessed on how far you are or have you been to the doctor? You ovulate about 14 days before your period starts, if you had sex with ONLY your ex 10 weeks ago there is a good possibility it's his baby. Sperm can live in you body up to five days. If didn't have sex with anyone in the two weeks before or after I'd say it is your ex's baby but you did not say if you had or not.
if there is more than one man you had sex with withing 2 weeks of each other only a paternity test will tell.