How would you take your ex-boyfriend's response of playing it cool when you split up with him for good because he was an ego maniac and loved attention from women?

The point is, why should you care? You need to ask yourself a lot of questions. Once you leave someone and even though you are hurting over the split-up it's simply time to move on. Many of us have had heartaches, but life marches on so you're either in the parade to the beat of the drummer or you're left behind. Let him ego-trip all he wants. The head of the snake always turns around and bites you on the butt. Meaning ... he'll get his in spades! Perhaps he was trying to save face. Maybe he didn't want you to think he was hurt by your breaking it off with him. Perhaps he sensed -- right or wrong -- that you were breaking up with him not so much for your own good but to injure him, and he didn't want to give you the satisfaction. Or perhaps he just doesn't care. The break-up could be no big deal to him. Perhaps you overestimated his feelings for you. If he is an egomaniac, as you say, and loves attention from other women, perhaps he's perfectly comfortable with being free to see other girls. He may be thinking, "It was fun while it lasted, and there are other fish in the sea."