Despite the headaches, the Charlton manager said he had been determined to hang on to his squad during the transfer window and turned down Crystal Palace's £2.5million offer for Euell.
Curbishley, who has a fully fit squad for tomorrow's game at Newcastle, said: "I said all along that if anyone was to leave it would be on my terms.
"I let Graham Stuart go to Norwich because he's 34 years old and, after all he has achieved with us, I thought it was right.
"When I look at Robbie Savage going for £3m and Barry Ferguson going for £4.5m, the £2.5m offered for Jason wasn't going to tempt me. I didn't want to sell him anyway."