Hi and welcome!
I just jad my first 100miles ride yesterday and it was great! You'll get more balls, as you go on.
I wouldn't go any smaller than a 250, 250 is just enough fun for an entry level rider. Maybe you can fnid someone in you area to ride with you, makes it much easier to relax. Just enjoy your ride and don't think about your in-laws too much, ride hard or stay home (without in-laws!!_)
Have a wonderful time riding and good to have you with us