I was like you, even said as much in a post a few above yours. This episode felt like it passed in about 15 minutes.
And you are correct, there are still three episodes. But, I was on IMDb trying to find the name of the Billy Joel song from the end of the episode, and I saw that the finale is actual two parts so penultimate next week, then finale part one the week after and the conclusion the week after that.
Does anyone know the name of the song? I think listening to the lyrics is what actually started the waterworks.