I understand that living with or dealing with a person with severe OCD can be frustrating and difficult, but when you let the anger slip, even if you say you're sorry, it can worsen the person with OCD, because it adds to his/her self-esteem issues, which most, if not all, of us have. We feel like a burden as it is, like we should be able to stop the way we act, stop doing the things we do, and control ourselves. When we aren't successful in doing that--especially when people don't believe you've tried--it hurts us more.

While I generally think it's better to be straight with people and tell them what you think, in cases like this, it might be better to tell your frustrations to someone else who doesn't have OCD, someone the OC won't likely come in contact with, or even knows. Not because you should talk behind people's backs, but because you need to vent, too...but you don't want to make the OC feel s/he can't trust you, and you don't want to tell someone who will tell someone else, even if that person won't come in contact with the OC. It's a matter of privacy and respect for people to keep your confidentiality.