Navigating feelings about the death of someone you had a strained relationship with

TLDR: how do you process and grieve the death of someone you had a strained and rocky relationship with? This may be a long post and I apologize, but it may be an interesting story to read for some. My husband and I have lived in our home for about 7 years now. We became fast friends with our next door neighbor who is a retired bachelor. We had a really strong friendship for a few years. Went to lunch frequently together, spent hours hanging out on the deck over the weekends, if he saw us outside he would come over and hang out with us and vice versa. About 3 years ago things went south rapidly. He accused my husband of stealing from him and slashing holes in his tires amongst other things. My husband denied the accusations and was pretty hurt that he was accused of this by someone we were so close with. Obviously my husband told him he did not do it but no matter what our neighbor wouldn't believe him and wouldn't let it go. Soon after, we had a series of unfortunate events happen at our property to include a popped tire on my husbands truck, our trash can being burnt to the ground, and our property being urinated on. Couldn't prove it was him unfortunately but circumstantial evidence speaks for itself. He also made sure to flip us off whenever he could and just stared at us whenever he saw us outside. The friendship was pretty much destroyed and over with at that point. Fast forward to now. Our neighbor is very ill and sounds like he is in his final days. I am just having trouble processing this information. He has sort of become a stranger because we haven't communicated (outside of being flipped off) in about 3 years, but prior to that we talked and spent time together almost everyday. I feel some sadness but mostly anger. Anger that he took advantage of our friendship and threw it all away and any chance at reconciling things is gone forever. In the back of my mind I always hoped he would try to approach us to apologize, but it sounds like that opportunity is gone forever. It just feels so unfinished and I am having trouble navigating how to feel. Additionally, my husband and I always planned to purchase his house whenever he decided to move and use it as an investment property. That just feels kind of weird to do now but I know my husband still wants to.