He says he's going to help me out, so let's see if he keeps his word. If he loves us, he'd help me nevertheless.
Is nevertheless okay here?
No. You might use "no matter what" there. "Nevertheless" needs to refer back to something else.
He's supposed to be trying to lose weight. Nevertheless, he ate six doughnuts for breakfast!
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.