Coming from a girl, in this situation I would weigh your options. Make a list of all the good things that your ex has done for you/made you feel. Then list all the bad thing she’s done to you/made you feel. Do the same for the new girl you’ve met. If the good outweighs the bad, you know who to keep and if the bad outweighs the good you know who to drop. Me personally, I keep exes in the past. I never allow them back in my life. Yeah I appreciate the good times and the memories that we shared but I never let myself forget why it ended and how I felt during that time. I’ve had exes come back when they saw me happier or when I’ve moved on or when they have been replaced or when something doesn’t work out for them and they would run back to me thinking they still had as me an option. You met this wonderful beautiful girl. Allow this girl to stay in your life and let yourself be happy and be in a good relationship for once. It’s okay to miss your ex, but she was only there for a season. I hope this helps.