What books can i read to help work on my emotions?

When i say 'yes', i mean 'yes and when i say 'no', i mean 'no'. But so far, this attitude has caused me so much pain. I say yes and get into whatever it is with all my heart and strength and expect the same level of commitment but i always get disappointed. I get hurt and i feel the pain deeply and for too long. Can someone advise on any books i can read to help me work on myself before i get consumed by my emotions? People have taken advantage of it for too long.