The keys to the old Apartment

"I was at some kind of wedding, not mine, and my ex-husband was there in the grey sweater he used to wear around the house, the one with the hole in the cuff. He didn't look older. That bugged me for some reason, like he'd cheated time. We were both holding paper plates with nothing on them and he kept asking me where the dog was, but we never had a dog. I told him that, I think, but he just nodded like I'd said something reasonable and handed me a set of keys. I knew they were for the old apartment, except the apartment was also somehow a train station? People were rolling suitcases past us and I was worried I'd missed my stop even though I wasn't going anywhere. Then it jumped and we were in the car, me driving, him in the back seat like a kid. He was laughing at something I couldn't hear. I kept trying to ask him why he was there but my mouth wouldn't make the right words, just mushy sounds. Woke up at 4am, heart doing something weird, trying to remember what the keys opened."