Can you love someone and be in love with someone else?

I hadn't been with he father of my daughter for four years and in that period of time I fell in love with another guy but that didn't work out. That was like a year ago. My ex and I agreed to work things out sincr April and I realized that I did miss him but I'm constantly thinking of the other guy. Should I keep trying with the baby daddy or break it off and give myself time to just let go of the other guy?