1) Don't say that to her - puts you in a needy position. You need to project confidence.
2) There's an old saying: "Hold your friends close, and your enemies closer". Not saying this guy is your enemy (or not even necessarily your rival). But if he's interested in your girl and has this much contact with her, it should be a priority for you to meet him. Maybe you'll find out he's a great, neighborly guy and you can be friends. Maybe you'll think he's a snake in the grass and have to keep an eye out. But the more you yourself are present in her life and not just an abstract statement that she makes, the better your position.
Now - all that being said - you've only been dating 9 months and she already is complaining that seeing you twice a week isn't enough? Is that because you're not a good communicator the rest of the time? Do you text or call her most days? Or is contact limited to around your dates? Have you been to her new home? (Or is she - wisely - keeping her dates separate from her daughter?) Do you make an effort to show her that she is special to you?
The most important thing to remember - if she were to pick another guy over you this early in the relationship (not saying she would, but if your fear came true) then she is simply not the one for you. Better to find out now.
