He's been sober 3 weeks now, am I wrong in thinking this is still early days?
Very early days and nothing to bet your future on at this point in time. He still needs to learn healthier coping skills then reaching for a bottle of booze when things don’t go his way. He still needs to learn healthier communication skills other than verbal abuse towards his wife when things don’t go his way, those under lying issues don’t just go away on their own or when the consumption of alcohol ceases.
Anyone can be nice, pleasant, and happy to be around in the short run it is that long hall that becomes questionable especially with an alcoholic who relapses. You need time to see what more will be revealed.
I might suggest that you set up a scheduled time for him to spend with the kids, much like one might be in place should you divorce and he gets visitations. See how he does with rules and schedules that will give you a good indication of his recovery.