*hugs*
Breathe...relax.
Be nicer to yourself...my first thought is, "what would a cis-woman do?" Would she be freaked out that he's a widower with a young son? No?
So your main concern is how he'll react to the truth of your situation, yes? Has he given any clues to this? Maybe he just wants a friend, or even if he wants more (but not from you), can you still be a friend? (You don't know how he'll react)
If you put out vibes that it's embarrassing to be trans, or an embarrassing thing to be seen with people "like that", you've set yourself up for failure.
Are you kind? Gentle? Sweet, in your own way? Potentially a good friend? Not so interested in bedroom things? There you go! If he doesn't want to see you again because of this...he's losing an opportunity to know a good person.
*hugs* again.
*offers a scented candle*