Blues slipped to 23rd in the Championship table after the defeat which also saw defender David Edgar sent off for foul play just seven minutes into the game at St Andrews on Saturday.
"You go into a game thinking you can win, only to concede an early goal, which seems to happen a lot at Birmingham," Crosby said after the game.
"Then we had the sending-off of David Edgar, all in the opening five minutes.
"The players couldn't pass the ball and kept giving it away as they lost their confidence.
"Bournemouth were bright going forward and at the end it was an embarrassment
"The circumstances before the game had no bearing. We were all in a good frame of mind to win.
"I picked the team and thought it could win. You cannot put the blame on anything which had taken place before the game.
"I have to take the blame because I picked the team. Obviously the players have to take responsibility because they didn't play well.
"The confidence drained out of the players. They have played badly because we let in eight goals.
"But those players have got to go out again next week and they have to get over this setback. It has been terrible day with apologies to the supporters.
"I didn't give the players time to have a reaction. I could have been in debate with them until midnight and it would not have been the answer.
"Whoever comes in as manager, I do not think he will have another performance like that."