It seems to me that there are five possible ways for a person to deal with emotional pain.
1) The first way that a person tends to deal with pain is reciprocation. This is the natural sinful desire to hurt someone back for the hurt that they've caused you. However, in our more ethically advanced society this does not always come out as direct backlashes, rather it comes out through hateful attitudes, indifference towards the person, doing the things that drive them nuts. Sometimes we don't even know why we're doing it, but deep down inside it traces back to the hurt they've caused us. A lot of times these hurtful / hateful habits start with one simple decision to not speak to someone or to not do something that we normally do to care for them. If we can stop ourselves from making that first decision to act in an unloving way it seems to me that we would keep ourselves off the slippery slope of reciprocation.
2) The second way is somewhat a halfway point between the first and third, so I won't say much about it. Sometimes we don't reciprocate to the person who offended us (for whatever reason, intimidation being a common one) but instead take out or emotional pain, hurt, and anger on someone or something else that is around us. It has been said, "Hurting people hurt people" which is often true, however I still believe it is only one of the options.
3) The third way that people deal with pain or hurt is to just accept it. They decide that it is not worth retaliating and they are not willing to make someone else hurt for them so instead they take it in and they just hurt, A LOT. Unfortunately this has been painted as the Christian approach to pain by many, but it is actually very contrary to the Christian understanding of forgiveness, but we'll get to that later. The problem with this approach is that our hearts, our emotions, cannot sustain this level of pain if we never release it, so this tends to come out in explosive anger or self-destruction. In fact, I believe that part of the rise of self-destructive habits in our culture (such as cutting) is due to the fact that option 1 and 2 have become less and less socially acceptable, as well as option 4 and 5 as we will see, so more people must turn to option 3, which only tears them apart.
4) The fourth way that people deal with pain is somewhat of a hybrid between option 3 and 5, so again I won't say much about it although I could (and probably should). The fourth thing that people do when they are in extreme emotional pain is to take it out on God. They get angry at God, they shake their fist at God, they yell at God, they curse God. Interestingly, most Christians would see this as the least Christian response out of any of those yet named, however when you read through the Psalms you start to get the idea that this may be as close to the truth as we've gotten yet. I believe that there is a place for this response to pain and hurt IF it leads us into the fifth way to deal with pain.
5) The fifth way that people deal with pain is to give it up to God. This is when someone says, "This is too much for me to bear, dear Lord, please take this from me." This was Jesus' response in the Garden of Gethsemane when he pleaded with God to take the cup from him, interestingly God did not but by Jesus giving up the pain, by him pleading his case to his father, he was able to then bear up under it. Too often people confuse option 3 and option 5 because they tend to have the same short-range results. When people take the pain on themselves the result is that they do not act out against another person, and when people give the pain up to God the result is that they do not act out against another person. However, the difference is not in what they do not do but in what they DO. The person who takes the pain on themselves becomes self-consumed, they either end up feeling high and mighty and like they are better than anyone else or they end up feeling like crap and hating themselves, but the person who gives their pain up to God is freed to love no matter what, to accept the circumstances (NOT the pain, that they've given away) and continue to love and live for God despite them. In fact, the person who has taken this approach will actually love MORE when they are hurt, because when they give the pain up to God they will see their own sin, their own faults, their own failures, and it will give them a compassion and sympathy for the person who has hurt them. In options 1 and 2 you don't love others because they become objects to inflict your pain on, in options 3 and 4 you don't love others because in your mind THEY should be loving YOU (because you have so much pain), but in option 5 you are freed from any of this and are suddenly able to love.
So cast your cares upon him because he cares for you. He is more than able to take them upon himself, in fact, he wants to take them upon himself. You don't have to bear them any longer, you don't have to cause others to bear them any longer, you can be freed and you can love. There is that split second when someone hurts you where you decide what to do with it. Some people immediately scheme about what to do back, others go and yell at someone or break something, others ignore it and simply internalize it, still others get mad at God and shake their fists; but in that split second, make it your conviction, your desire, your impulse to turn to God and say "Father, take this cup from me, it is more than I am able to bear. I know that Jesus already took this pain upon himself, I know that he already bore this sin, I know that he loved even when he was spit upon and beaten, send your Holy Spirit to put the same love in my heart."