I am 25 yrs old. There is this girl I go to school with. She is 31 yrs old. We get together very well, we talk, laugh she even invited me to a bar-b-q yesterday. She recently acquired a boyfriend who is her age. I have feelings for this girl and I have no idea what to say to her or even how to say it. What should I do?

Does she know that you like her or does she think you are just a good friend, cause that is what it sounds like to me.

Because she has been friendly, doesn't mean she is interested in you romantically. She has a boyfriend, so keep your feeling to yourself, and be her friend, although less available.

It is very common for men and woman to be friends! Most of my friends through my life have been male, yes I'm a female.
Stay friends with her, enjoy your friendship.
Tell her? That's an iffy. You could, if it bothered you. However, telling her could either end your friendship or nothing at all. Is it worth risking losing her as a friend?

You should leave her alone since she has someone. Did these feelings come on before or after she meet her b/f? Any I think you should back off little and try not to be around her much since you have feelings for her because your feelings will grow. In the meantime find someone that is single for yourself and let your feeling grow for her only if it mutal. Also, you might just have a crush so let it go and don't worry your get over it.