Given your weight, you might want to ask in the Clydesdales/Athenas group. You want a bike that has wheels with enough spokes to handle your weight otherwise you are going to have continuing mechanical issues.

Congrats on the clean and sober! I've known several people who have been over 300 pounds and with regular hiking and/or biking and developing good eating habits have lost 70-150 pounds. It's pretty awesome seeing the immense change in life it has brought. I have great admiration for these folks.