Getting over boyfriend’s ex

Hey guys, just a little back ground. My ex of 3 years broke up with me about 2 months ago. However, I just recently started seeing a new guy and things seem to be going fast but great so far. We’ve only been dating 2 weeks but have known each other a month and a half but it seems like we’ve known each other much longer and have become great friends. Hes 23, I’m 20, and he’s been very honest and open about his past, which I appreciate. He’s been with 3 girls and I’ve only been with one guy. 2 of the girls he’s been with were just hookups but the most recent one he lived with and was with for 2 years. I’ve been kind of struggling with jealously over this. I guess I’m just scared he would still have feelings for her after being in a serious relationship like that. Have any other ladies dealt with stuff like this before? Thanks guys ❤️