Matt Pennington’s thumping goal – his second in successive games – seemed to have set up a first away win since Blackpool.
But Reading, who had threatened little, scored twice in the closing stages through subs Paddy Lane and Matt Ritchie to clinch an improbably comeback victory.
Alexander called City’s fifth straight loss on the road a “real stinger”.
“I thought we were a different class for 85 minutes, actually, all the way through the game,” he said. “I couldn’t see them scoring – we just had to defend our box.
“I think we defended our box well enough for the majority of the game. We absolutely bossed that game; it was a superb performance.
“There are a couple of bits and goals that we can do better with.
“You’ve got 11 players who are all connected and all working as hard as they should. It was the best away performance for me, better than Cardiff although not the result, obviously.
“The way we passed the ball was superb and we should have won that game.
“I’m devastated for the players because they deserve better than that. But we have to look at what we can improve in that last five minutes.”
Alexander insists the way City played should give them confidence on their travels despite what unfolded in the dramatic finale.
“I’ve said to the players, today was the start of the rest of the season away from home for me.
“I’m not boxing that off with the other games we’ve played since January because I thought we were a different class today.
“The result is an absolute kick in the whatsits. I think it was undeserved.
“I thought we were the better team throughout the game and so comfortable.
“We had a little meeting last night and I said that all I’m looking for is a performance from a top team, which you are, and that’s what we got.
“What happened at the end can happen in any game. You can play so well for 89 minutes and then things like that can go against you.
“They’re committing bodies to the box. We’re probably not getting the pressure from the front as well as we have done for the rest of the game.
“It’s a game that we’ve seen out so many times. But sometimes life tests you and I said that to the players in there.
“This is one of those days when in recent away games, we haven’t deserved anything. But we deserve so much more from today.
“So sometimes it’s just a test of your mentality. The big man upstairs actually tests you out and says, ‘OK, you play well, well done, but you’re going back to nothing.’
“We have to show what we’re about next time and I think we will.
“I think the players showed today what a good team they are, what good individuals they are, what great characters they are and I think they’ll continue to show that.
“But I’m not going to shy away from it. It really stings and I can’t take away that sting and that pain until we get back to work.”
Aden Baldwin went off midway through the second half with a suspected broken nose.