Losing a spouse can change a person drastically.
It did my dad when my mom died in 1987.
It’s possible your “exfriend” may blame God for the loss of his wife......and by extension you as well.
A friend in my men’s church group shared a similar story recently.
Someone he knew that was a nonbeliever lost a family member and lashed out at my friend almost immediately saying “where is YOUR God now?”
Sometimes all we CAN do is pray for them.