Bart Griemink was in downcast mood after his goalkeeping blunder sealed Town's defeat on Saturday.
The Dutchman's shanked clearance ballooned vertically into the air and presented visiting striker Kyle Lightbourne with an unmissable opportunity to score Stoke's third.
Griemink made no excuses for his 78th-minute howler.
"My kicking is usually pretty good but that was shocking," he said.
"After that mistake, I completely lost it. I got another back-pass and I should have kicked it out. I didn't know what I was doing.
"It was a terrible afternoon. We lost 3-0, I made a big mistake and I'm going home disappointed."
He admitted that Town's defence looked shaky throughout.
"It looked like they were going to score every time they got a corner. The first two corners they got they scored. That was not a good start and we were chasing the game.
"They got a flick-on for the first goal, and it was an own goal. With the second, they put really good balls in and he got a flick-on and it went in."
Town's players did not emerge from the dressing room for almost an hour after the final whistle, and Griemink confirmed that the squad had been asking themselves some serious questions.
"We had a long inquest," he said. "We all know that we've played badly. We are letting ourselves down big-time. Every time we get chance, the crowd is behind us but then we let in bad goals.
"It seems to happen in every game at the moment and it is not good."
New loan signing Richard Dryden made the worst possible start to his spell at the County Ground, putting the ball into his own net after just eight minutes.
He said: "It was a very disappointing debut overall. We lost the game in the first 15 minutes. At 2-0 down, we had a mountain to climb. We had the majority of play in the second half, but the third goal killed us.
"I was at Northampton Town in this division two months ago, so I know what to expect. This was the worst start possible."
The Southampton defender explained what happened with his own goal.
"It was like slow motion," he said. "I had the flight of the ball and somebody just got a nick to it and took it off its course. I didn't know whether to head it or kick it and it just ended up in the goal.
"For the second goal, Kyle Lightbourne got up pretty high and it went in the top corner.
"That totally deflated us. If the first one didn't the second one did."
Dryden denied that it was difficult for him slotting into an unfamiliar back three.
He said: "It is not difficult to settle in. There can be no excuses for our performance. It was pretty poor and everybody is really down and out.
"This was the sort of week when you want a game on Wednesday to bounce straight back."
The 31-year-old feels that Town have the mental strength to overcome their problems.
He said: "When you get beaten 3-0 at home, Saturday nights are not the same. But there is good team spirit here. We have got plenty of guts and commitment here, but if you go 2-0 down after 15 minutes, it deflates you."
Dryden confirmed that he would love a permanent move to Swindon.
He said: "This part of the world suits me. It is lovely and it is ideal for me in terms of friends and family.
"I haven't made a great impression today, but fingers crossed, there will be more games to do that."
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