Whose the dad?

Hi guys! So this is a bit of an embarrassing topic. I’m pregnant and have had my first ultrasound already to confirm. Due date august 9th so I’m a few days over 8 weeks. I literally can’t remember the date of my last period because before I found out I was switching birth control methods so my periods were on and off and irregular. The issue is I was in a long term relationship that ended in the beginning of November. I was in a bad place and after that I partied a little and slept with someone else a few times. It was only one other person but I was drunk and it was unprotected. I went back and found a message to my best friend saying the night we had sex unprotected was November 19th. But if I’m a little over 8 weeks that puts me already being pregnant. So the question is..could it be his or would it definitely be my ex partners ? Please help this is so stressful and I know I’ll have to get a test done I just have so long to go before I can do that.