Found a guy way better than my ex but still hung up on him

Ladies, I need help!! My ex and I broke up back in October because of distance (we both still had feelings, the relationship just became unrealistic and we have too much going on). It crushed me even though we only dated for like 5 months- we moved really fast and he became a huge part of my life. Anyway, I went on a double date with my best friend last week, it ended up going super well and the guy and I hit it off. He literally treats me SO well and does everything I'd want a guy to (literally cooked me dinner at his house, has taken me out to dinner twice, seeing him again tomorrow- this is all in a week) but I'm still fucking upset about my ex. I cried on the way home from dinner with the new guy (in my car by myself dw) because I still miss my ex for no good reason at all. He gave up on me and I have no time for that, but he's still in the back of my head. How can I get rid of this to focus on this great new guy?? I'm so frustrated :(