yeah I think I covered that she took her anger out on him and made it personal and insulted him
Yep, she clearly went too far. The gist of what took place there is that she and Cole share a bit of a special relationship, one she's clearly aware of, and it started on that very first night they had dinner together -- when she learned that he lost his daughter, and his marriage couldn't survive the event. What Cole was attempting to tell her, no matter how much she may try to view it as a rationalization, carries with it special significance to Cole, and I feel she understands enough about him at this point to not simply cast aside what he's trying to say.
An important focus in their conversation wasn't so much Hart and her, but the importance of the children being apart of Hart's life, and how, in his view, it's the best part of a marriage. When someone loses his daughter, as Cole did, I would take him at his word when he stresses the almost extreme circumstances that one should be willing to put up with to not break that bond between parent and child. Even if it's, as Maggie says, Cole's own rationalization, stemming from a traumatic experience in his own life, it really shouldn't be generalized as being the exact same as any other man's appeal on the importance of being able to be apart of his children's lives. Maggie has every right to be angry, but I think even she herself realized that she crossed the line a bit with that dismissal of hers. The message in that scene wasn't that Cole didn't get through to her, or that he was the one in the wrong, it's that Maggie, in her anger, was pretty insensitive considering what she knows about the man. There were other ways to end the conversation with Cole without giving any ground to Hart for fucking up, and I think Maggie realizes she chose the wrong route.
Hell, she even clearly enjoyed his company when he was at the house helping out. Remember when Cole came to get Hart from the hospital? Cole and Maggie have an understanding of sorts (take note of the looks and slight nods the two of them exchanged), which makes her dismissal even more cold. I don't exactly condemn her for it, but it could have been handled better.