Chelsea lost 3-1, though had the lead until the final 25 minutes as Brighton took advantage of Trevoh Chalobah's 53rd minute red card.
"I would say the first half was good from our side," the 19-year-old told the club's website. "We had a lot of possession, we created chances, we scored to make it 1-0 as well. We were playing well and scored a good goal.
"In the second half, after 10 minutes we got a red card and went down to 10 men. After that we knew it was going to be a difficult game, but all I can say is that this loss is very disappointing."
Hato added, "Of course in the last game against Man United in the first half we also had a red card and now it happened again.
"You can see it just affects the game, when we are down to 10 men against 11, and we did it for nearly 40 minutes yesterday. You can see it’s very difficult.
"We knew of course they would be playing on the sides and coming in with crosses. I think we could have done better, for sure.
"We’re very disappointed because we knew it would be difficult, but I think we didn’t give a lot of chances away before their equaliser. So, as I said, we’re very disappointed."