I don't know why she acts this way - could be a lot of reasons (fear, loneliness, not having her own personal boundaries, etc.). But it seems to me she has taught you a valuable lesson, which reminds me of the video that is no longer on YouTube of Madea talking about how people are like trees. Some are leaves, they belong in your life only for a season. Some are like branches, they may bend and break occasionally, but they are trying to be strong. Some are roots; those are people who you know and have relationships with for a long time.
Every person who comes into our lives teaches us something, even if at the time we are not aware. This woman taught you to recognize your own internal voice telling you where your level of comfort is. My friend, the one who I mentioned above, taught me the same lesson. It was very helpful (in hindsight).
And so happy for you on the new BF. He sounds wonderful! ; )