Does one have to suffer pain to become a stronger person?

To have to suffer through negative situations and emotions surely must be one of the most difficult things a person can encounter in his or her lifetime. To come through these situations and still have the courage to continue on shows strength of character and persistence in looking for the better things in life. Because you have experienced some of the "worst" in people, you are more aware of your own actions and I don't doubt that you try to avoid such behaviors in your own life. Good for you, this has actually made you stronger and better than you may believe. I'm at a loss to understand your statement about jealousy and guilt increasing and why it would do so, but I encourage you not to dwell on the negative stuff, just keep on with what seems like your good judgment and try to accept the fact that other people do what they do because they have free will. They (obviously) may not always make the wisest decisions, but in the greater scheme of things, they are also learning from their negative behaviors in some way. I wish you good luck in your learning experiences in this life.