Advice needed

So I need some advice...

about 2 months ago my boyfriend of 3 years and I broke up. I broke up with him cause I didn’t feel I was in love with him anymore. But I’ve had a new boyfriend for about a month now and at first everything was great but then he started getting really jealous. This is something I’ve never had happen before. So it’s just really overwhelming. But the last few days I’ve been missing my ex. I had to move cause of my job so I’m no longer around my ex but it’s like I feel like I really f’ed up everything. I just find myself missing him all the time. Idk if it’s because I’m actually still in love with him or if I’m just missing the relationship cause it was easy.

Any thoughts?