How to let your friend know, you liker more than friends?

I know this should be an easy thing to do, and yest for some, it may be. But this is hard for me. I met this girl at work, we started talking at work. Then one day, she gave me her number, and asked for mine. Since we have become real good friends. We go out to eat a lot. She has also let me meet her 3 daughters. Well over the past couple weeks, I am starting to like her more. But just afraid to tell her, because may lose her as a friend. At times, I feel like she may like me, but not sure. Just little things that she does. Well I told her I was moving away in a couple weeks, to Michigan, to get a better job. She asked me not to go. But then at times, she acts like she don't even wanna speak to me. Then one day, her middle daughter, said to me, that her mom said I don't care about her? I asked what she meant, but she wouldn't tell me. Well I will be leaving in about 3-4 weeks, and I just want to let her know how I feel before I leave. But just don't know how to go about it. Any help is appreciated.