But the more I think about it, the more upset I am that he’s even opened up us to this by crossing lines with this woman.

What lines did he cross?

I confronted him after finding out people thought he was cheating on me, saying that people are accusing you of this and you need to stop making it look plausible.

Why not just set them straight? You and he BOTH help this woman out where you can. He's being a good Samaritan, and they should stop jumping to conclusions and mind their business.

but I didn’t really get the sense that he thought he had been wrong in the first place.

Neither do I.

On the other hand, him being helpful to people in need is very normal for him, his grandfather was a minster and while he's not himself religious, the whole idea of going over to have a cup of coffee with an lonely neighbor or helping someone with a side project or just listening to someone's problems is very familiar to him.

That's the kind of person my grandfather is too - and my uncle, my mother, my brother, and myself. We've got a whole family of people who go out of their way to help strangers. And it makes me really sad that you can't see past the town gossip to the genuinely selfless intent behind your actions. You should be standing up for your husband, not telling him to stop doing what's in his heart.