HELP ! PLEASE !

let me start by saying I suffer from anxiety and I am an extreme over-thinker. I have been with my significant other for three years. last may we broke up. While on The Break-Up I had sex with someone else. Me and this other person use a condom and I seen him pull the condom off afterwards. It didn't appear to have any leakage/tears because I didn't see anything drip from the condom when he took it off. I found out I was pregnant in June . I had my daughter a month early I was supposed to be due next month. my daughter does not look like either me or my significant other. I am terribly worried that it could be the other guys even though we used a condom. Please tell me if I'm overreacting or does this sound like a realistic possibility ??? Ik I messed up & I've learned my lesson but this could completely destroy our family. HELP