guilt trip

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A usually prolonged feeling of guilt or culpability.
• idiom (lay a guilt trip on) To make or try to make (someone) feel guilty.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun idiomatic A feeling of shame or embarrassment, especially if self-indulgent, unwarranted, exaggerated or felt over a significant period of time.
• noun idiomatic Remarks intended to produce such a feeling.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun remorse caused by feeling responsible for some offense