Stepson's mother died

My husband's ex-girlfriend and mother of his 9yr old son died last week in a car accident. She had been cut off from my stepson since last May due to drug use, we tried everything to get her into treatment but she wouldn't go. He told me at the time we were trying everything to help her because he expected her to die of an overdose in the near future, I thought he was exaggerating. He had a great relationship with her family and we are going to the funeral. How should I feel about him mourning his ex? They had been split up for years when we met and he made it clear there were no feelings there anymore, they just shared a son. She was always nice to me when she came over to visit her son as her visits were supervised in our house.

How should you feel? Never mind that - how *do* you feel? And how would you feel if you heard your last ex-boyfriend or first-ever serious boyfriend had died, but with whom you'd had to keep in regular touch due to whatever circumstances?