Well... a good way of telling, is see if you can find something that annoys you about him, laugh about it, stick your tongue out at him for it, and know how annoying it is. And still love him all that much.
If EVERYTHING about him is good and he is PERFECT, you are idealising. If he is imperfect, but perfect for you, you're just head over heels in love so enjoy it.

you can be healthy and feel that way, its just up to you to figure out how much you can do by how far towards healthy you are yet...
With BPD i think its easier to let go & love someone when they are at a little more of a distance, so watch out for that when you see him again don't dive in too far or you'll end up on the whole push-pull thing... so i guess enjoy, but keep perspective too!
all that side of things out of the way, congratulations to both of you!