Same here. Sure, I wanted Cersei to be gutted by Arya, but people don't always get what they deserve. In fact, things rarely work out that nicely.
Did I think Jaime and Cersei's ending was romantic? God, no. I thought - these two were fucked up from the moment we met them, they remained fucked up, and they died fucked up. I mean those two were FUCKED up from childhood. It's not easy to pull yourself out of a totally twisted and abusive relationship and Jaime wasn't able to do it either. The love of a good woman is not enough. It just isn't. That whole ending was so sad to me, as someone who grew to really love Jaime, but so realistic. It also reminded me of him telling Cersei in S1 that he would be fine with everyone being killed until it was just the two of them left in the world.
You are not the only one. I started rewatching season 1 last week and I'm not surprised by this from Dany at all. I think, for me, I was always on her side because of who she was up against, but she always had a very unsettling response to seeing her enemies vanquished. Now she's going up against people I like and it's a total mindfuck. I'm enjoying this in a masochistic sort of way because I'm on her side in so many ways, but she is clearly in the wrong. She was betrayed by Jon and Tyrion and, coupled with everything else, who wouldn't lose it? I do think it was way too rushed though. WAY too rushed. But, for me, it's not out of left field at all.
When she killed Varys the way she did, I also thought of Ned's lesson about the one who passes the sentence must be the one to swing the sword. Dracarys indeed.
You are not the only one. I'm sad, I'm angry, I'm disappointed, but none of it feels out of nowhere to me.
The Tyrion/Jaime scene was beautiful.