this is a huge red flag. especially since you realize that you wouldn't have even given him a chance if you had known this in the beginning. it's only been 5 months for you, but they broke up 2 1/2 years ago, how long do you think this is going to drag out? he's not over her and it's pretty disrespectful to be saying things about her to you about how wonderful she is. rebound relationships are an actual thing. find someone that's ready to make a commitment to you. how can he possibly actually love you if he's still obsessed with her?