Too much jealousy in friendship is not healthy. A year before last , a young guy passed on, just because of jealousy from some of his friends with wicked intentions. The guy was becoming wealthy and had established businesses in town. At a certain point he was planning to travel out of the country , and the friends got to know. As the story have a week to when he was about to travel, he decided to sit out and have some bottles of drinks with friends not knowing that some friends smiling with him were actually jealous. After drinking with them, his drink was poisoned and that was the end of the story. At times we just need to be wise and so sensitive, because jealousy can lead some people to act in the negative direction.
You might not really know who is jealous, but at times you will notice them being too competitive, or trying to get to know every details about you. My guy told me some days back about the character of one of his friends. According to him , when ever this friend visits him and noticed that he has gotten a certain thing, the guy will also do everything to get that same thing after few days. And this keeps happening for some months. And all I could tell him was to be extremely careful, because that was a sign of jealousy.
On handling jealous people, we must all learn to be sensitive and trade with caution when we are around them, because they will always do any funny thing one day and blame the devil. If possible, keep a distance, because some of them are friendnemies. Again, mind the information you dish out to some people, because someone telling you congratulations doesn't really mean he or she is happy with you.
Lastly and most importantly, I will always say always pray to God for protection.