My best friend has a boy friend and I used to hate him but now I have strong feelings for him even though I should not. I am worried if she finds out if she'll be mad at me and what he thinks about it.

We can't control what feelings we have, or for whom, but we can control what we do about those feelings. Don't cross the lines of good behavior, and keep your fantasies to yourself.

Girlfriends you will have all of your life if you treat them with respect, and honour your friendship by being honest, and considerate.

Boyfriends will come and go.

And when the right one comes along, your girlfriend will be there for you.

Keep your feelings to yourself. This is not a good thing to act on. What he thinks is immaterial.