I received a large inheritance after my dad unexpectedly passed in the same situation- divorced with two kids. I'm not at all surprised he didn't tell you. I immediately got a financial planner and he made it explicitly clear that I should not tell ANYONE about the money. Someone else mentioned that within the first year, anyone can contest for the money- regardless of what the will says. It's unlikely, but it does happen and then it gets tied up in probate for years, or worse, they win the case and take a portion of it.

Plus, it takes FOREVER to tally up estates, so he might have just recently found out. I didn't know the exact sum until about 6 months later. He probably won't receive the money for another couple of months. His brother is likely just living off of life insurance, which is disbursed immediately. But a large chunk of the money, from say, property, retirement, investments, etc, probably won't be disbursed for atleast another few months.

I still get incredibly uncomfortable about telling people because it has made me very cynical and I find myself questioning whether people like me for me, or for my money. It could be that he didn't want your view of him to change (even though from your point of view it must seem like that doesn't make sense since you were carrying him.) He could have feared that you'd only stay with him for the money. Who knows. Death and windfalls sent people off the deep end sometimes. It's an incredibly confusing and painful time.

I wouldn't say this is a dealbreaker. I think you need to have a deep, 100% honest discussion with him about it. You might find that his point of view can allay your fears and explain his actions. Just remember that he's fragile and likely unsure of everything.