I remember breaking the no contact thing many times. Believing, hoping, wishing, etc that things would have gotten better. I remember also breaking that no contact for my own selfish reasons - I wanted to see him, I needed to see him, I missed him, etc. but looking back now, I know that I caused myself a whole lot of grief that I could have spared myself if only I'd not broken that contact. Then again, I suppose it was in breaking that where I came to keep seeing and being reminded that it really was better for me in the long run to remain in no contact mode.
Perhaps you can see this not only as a blessing in disguise (which I believe it is), but also maybe stop to think that maybe somehow your HP is stepping into protect you. Again, another blessing.
Yes, it hurts. But doesn't this hurt a little less than living in that dramatic chaotic state of constant contact with him? Do you remember what that was like?
PIck yourself back up and brush off - and get back to recovery. YOUR recovery!
It's okay that you slipped - it's now up to you how you choose to handle that slip.