The Reds looked to be in total control after a Craig Westcarr header and a Brendon Daniels free-kick saw them go into half-time with a two-goal cushion. But the hosts fought back and grabbed one back on 48 minutes before the Reds imploded late on, conceding an 87th minute Jason Gilchrist equaliser from the spot before the winner from Joel Logan on 89 minutes.
McDermott told the club`s press officer Amar Sharma: "We went in, we came off the pitch, we went in at half-time. I don`t know what happened between me telling them what we wanted. If anything, we needed to tighten it up in certain areas and not see the game out but tighten things up and we would be alright.
"We collapsed, poor goal to concede the first one. The problem, and it`s been all season has been in our box. We can't defend our box and we are meant to have one of the best back fours, back three's in the league. I feel embarrassed for the lads because we threw away a two-goal lead, we didn't see it out and I'm hurt and I'm angry.
"The first half was great, we were excellent, and I warned them at half-time that they would come out and we need to be on our toes. We didn't stay concentrated."
On the goal times, McDermott said: "It was poor goal times, poor goals for us to concede. First one we want to head it back across our own goal instead of clear it. Second goal, they are stretching us, they are working harder than us. It's a stupid penalty to give away, the lad isn't going anywhere and we dive in, needless.
"Third goal, we have a chance to clear and we don't, they get it on the wings again, not really going anywhere but the lad turns us like a good turning on a bus and to be fair if Chris Elliott hasn't pulled off some fantastic saves they could have had more. They were excellent and credit to them for taking it to us and fighting back to win the game."
On producing a reaction at AFC Telford United on Saturday, McDermott added: "It's huge, the lads owe a performance and they owe a shift. They have to bring it on Saturday. They owe the fans that, the fans that travelled up last night, I apologise for the performance and the manner at which we threw the game away, we went under like a pack of cards. The fans didn't deserve that after such a good first half.
"Everything was working, the system was working, it got us two goals up. We praised the lads at half time, we were stronger, better but the second half all that was undone.
"But our organisation, our work rate it was poor in the second half and it's disappointing. That's cost us goals, basic defending yet again. Both teams were the same in the second half, they didn't send out another eleven. They just worked harder, they were more physical, we didn't match it. Our system didn't need to change, theirs did and we didn't work hard enough.
"Again, sorry to the fans for last night's performance, it needs addressing, we can't go under like that. It hurts to lose in that manner and Saturday we owe everyone at the club and that supports this club a performance after last night".