The main thing is to keep your wheels well-maintained.
I weigh about an eighth of a ton---a little less than you---but I have been riding for years on 24- and 28-spoke wheels, with no problem.
Spokes break for two reasons, in my experience---potholes and similar sharp impacts---- and Being Too Loose. Check you wheels frequently---tap the spokes and listen for low-pitched vibrations.
As far as buying a new bike---go for it. But choose very carefully. Maybe consider a cheap bike as a back-up since you probably won't be riding it that often--How often is your main ride in the shop, right?--so maybe consider a decent used bike, and then in a few years, as your fitness improves, you can decide what you might want based on your needs and wants at that time.
Yes .... big people can ride, and love rising .... so keep living and riding and enjoying.