I've fallen head over heels and I know I shouldn't have.
Why did you let yourself fall in love if you know you shouldn't have?
Because I can't control my feelings anymore.
If you know that they aren't right for you then this could end badly. Try to control your feelings for this person.
It's like they say, "You can't stop love when it strikes."
I think that you need to try to be more aware. It is bad to fall in love when you know that the person is bad for you.