for thoughts I cannot express anywhere else

I've been treating other people so badly in the past few weeks. I have been very ill-tempered towards my friends that I cannot be subtle about it anymore. I want to change my perspective. I want to be nicer to people and talk to them with a happier attitude. Let not anger rule over me. I must be happy. I must see that there is a positive thing in everything that I encounter. Help me God, please. I want to change my life.