Is it possible to love two people? Or love one person but not quite be over the things that happened in the past?

Say you’re with someone who makes you so happy, but at the same time you wonder about a person you loved previously and miss them (to an extent)

I know I’m a horrible person and the kind thing would be to break up with the person I’m with now, but I honestly do have feelings for him. I feel like I’m so scared of letting the past happen again and that’s why this could be happening?

I don’t know if I make sense. I’m really confused.

Any advice would be greatly appreciated. Or if anyone can share their experiences with something like this?