I am sorry you got this news, but you are correct, it's the best of the bad news.
From what I know, making these decisions can be extremely difficult. Please take your time, and while it sounds like you are at a great hospital, think about getting a second opinion, or third, even. Like maybe at Dana Farber? You're so close, it wouldn't hurt.
Because I have no personal experience with this, anything I can say seems silly. But, feel free to PM if you need to vent.