Ex contacted me

So yesterday I get a strange phone call.

It was from my home state, and because they were being so persistent I thought it was a family emergency.

I answered and it was my ex! I panicked and told him I would call him back and hung up since I was with my fiance and roommate going to run errands.

I proceed to shake and cry and disassociate for about twenty minutes and I'm still dealing with it today. I have no idea what he wanted when he has a fiance and son at home. He seemed so happy to hear my voice and to hear that I was driving (I wasn't but I was in the car)

It broke my fucking heart. We didn't end on good terms and I was in love with him for a long time after the break up. I still care for him as a person and I only want what's best for him.

What could he have wanted? What do I do if he contacts me again?