The best thing to do is to take things slowly, flirt with him a little bit and see if he responds to that.
I understand the pressure on you, making a move only to be rejected would be mega-embarrassing because you risk having your entire family find out.
No matter how nice or sympathetic they might be, it'll still feel pretty bad of things don't work out.
That doesn't mean you should give up though. When true-love comes knocking, you can't afford to ignore it.
So the main game plan to stick to is:
- Flirt and be extra nice to him
- Arrange situations where you guys spend time alone together having fun. Maybe go see a movie or something.
- Stay cool, calm and confident. Guys tend to like a girl that knows she is fun to be around - so try to get all thoughts of insecurity or shyness to the back of your head.
- Be yourself. The two of you are going to be spending quite a bit of time around each other anyway (as long as your mom keeps dating his dad), and you can't pretend to be someone else forever. Just go with the flow and you'll be fine!