If he could miracle himself some dignity, he would, but he never anticipated an apology like this. While it lovely to hear those words, Crowley doesn't feel deserving of them, and it's causing a whole mess of emotions to spill out at once, having pent them up for some time.

"Angel..." he breathes, speechless, the little kiss to his hand and the promise that came with it squeezing his heart in his chest. All he can think about is how much he loves Aziraphale and never wants to let him go. His legs slide to one side of him so that he can look into his eyes again, his own blown wide and vulnerable. 

"I could never hold those things against you." he attempts, his voice significantly quieter than before, trying to remain collected. "You're my best friend, angel, my world."