The Latics were seemingly cruising at 2-1 up early in the second half after Roger Espinoza and James McCarthy scored either side of Angel Rangel but later lost two goals to Itay Shechter and Dwight Tiendalli to remain three points from safety with two matches remaining.
Martinez's side got things back on track with a come-from-behind 3-2 victory over West Bromwich Albion on the weekend but performed the opposite in losing to the Swans and resigning their survival fate to the sides above them which frustrated the boss.
"Everything was under control with our first half performance. We were performing really well, but then in the second half with the goal that we give away, from that point on it becomes a very, very difficult game," Martinez told Sky Sports.
"We have so many injuries at the back and today that showed too much. We conceded sloppy goals with bad decisions. That is very unfortunate because you could see the effort of the players and the commitment and desire in wanting to win the game.
"You always get situations in games where you can recover. Emotionally today was such an important game for us, playing at home, that it becomes a difficult performance. When you make a mistake in that manner it becomes a bigger mountain to climb.
"What we must do is make sure we get ready for the next two games that we have got in the league and make sure we get everyone as recovered as we can.
"The team is ready to bounce back and make sure we take the opportunities over the final two games. We have got incredible character and we are determined to fight for every single point that is left.
"There are six points there to fight for and we need to make sure we can learn from this for the final game of the season. We have to accept nothing went our way and we need to make sure we turn it around quickly for the final two games."