The best teachers you meet will never feel sorry for you. They won't pamper your weaknesses, glorify your emotional traumas, or give you time and space to feel sorry for yourself and complain about how much you're going through. The best teachers will not let you cry on their shoulder day after day or take it easy on you, waiting for you to gather yourself. The best teachers probably won't be nice and social and friendly, and they will never be someone you'll feel too comfortable with. Chances are, you'll fear them. There will be moments when you hate them. There will be moments you wish you've never met them, and you'll curse, and run away, and think that life in unfair.
But at the end (not end "End", but the end of every fit you throw on your life path) it will become clear that all the best lessons come from these people who were like hard, unfriendly, distant, and unbreakable rocks sticking out of the ocean depths... People you thought would break you to the point of no return.
PS. Everything in life can be taken as a lesson but it's also important to be aware and distinguish teachers from abusers though. Sometimes there is a very thin line in between.