Reddit reviews The Power of No: Because One Little Word Can Bring Health, Abundance, and Happiness

Short answer: It's not you.
Long answer: In some ways, we "teach" people how to treat us. This doesn't mean you're at fault for how others act! What it means is, when you let someone take advantage of you, even if your intentions are kind, a bad person will keep doing it. Many people will start pushing farther and farther until something like this happens, and you SEE that something is really wrong.
I think you need to distance yourself from this person or at the very least put up strong boundaries. He needs to know that you will not let him treat you badly and then use you when it's convenient for him.
One way to deal with feeling like people take advantage of you all the time (I've been there!) is to stop helping people. I don't mean that in a malicious way.
I'd recommend taking a look at this book. (http://www.amazon.com/The-Power-No-Abundance-Happiness/dp/1401945872) I know it looks like just another self-help book you'll never use, but I started reading it one day and got through the whole thing. There are a lot of great anecdotes and examples of how to set boundaries while still keeping your faith in humanity.
Best of luck, friend. :)

Niiiiice! Glad you put the jerk in his place. Upped your confidence, huh? :)

That reminds me of James Altucher's bestselling book The Power of No (http://www.amazon.com/The-Power-No-Abundance-Happiness/dp/1401945872). Definitely worth the read! Sounds like folks are waking up to the power of unconventional wisdom.

Try this book: https://www.amazon.com/Power-No-Because-Abundance-Happiness/dp/1401945872