Why do humans have so much hate and jealousy towards eachother?

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I got married on saturday and everything was great except one thing... my mother in law would not look at me or shake my hand or congratulate me or even hug. I didnt think much of it at first, I just felt totally disrespected!!! Then came the reception, everything went well but I got tired and wanted to leave at 10:30 so I made my husband, who could have stayed all night, go back to the hotel with me and spend a little alone time together. Everything was going good my parents went and danced a slow dance together and then my mother in law went up to them and asked where I was, they said we were tired and went to the hotel. so my MIL (mother in law) started saying how their daughter, me, was a FU$@*n BI&%h and this wedding should have never happened and I made him leave and he was having fun so I am a B%$ch. Then my husbands cousin started in and was saying the same types of things. Now I could see if we never got along before but we got along the whole week before the wedding up until the rehersal dinner and the wedding. So my questions are.... What the heck makes people so angry and have so much Hate and jealousy and my second question is how do I ever forgive and move on when they wont apologize? I am trying to do the Christian thing but man it is hard. My mom says to think of the good things and I do but I still cant help to get so angry and think of the huge fight that broke out after those words were said about me. My wedding was almost ruined. Help me!! I blame myself for being so tired and leaving early, What so you think????