We met a recently bereaved man on a cruise and his story was very similar to yours. Such a lovely man who used to save us a sunbed in the mornings 😎
Anyway, this was his first cruise without his wife and he joined in everything going and was really surprised at how easy it was and much fun he had. He had his 'moments' and sometimes took himself off somewhere quiet and that's fine, that's how he coped.
Strangely enough we don't do many cruises now that he isn't on! He's living his best life and although I never knew his wife I'm sure that's what she would have wanted.
Good luck with whatever you decide - sometimes the first step is the hardest.