yeah exactily^^. Don't let the small stuff get you down. I know it might be big right now but it will work its self out. You do just need to chill, maybe with some close friends, and just bake and think about it.
Don't let your grandpa get you down. It does happen, its hard I know, but he really is in a better place no matter what you believe in.
Your chick, you need to get rid of her. I was in a situation like that too and things never got better until I got rid of her. She will do it again no matter what she says, mark my words. I know I don't know either one of you or the situation but cheating says much more about someones personality than you think, she doesn't respect you are the relationship and she never will respect the relationship. There are a shit load of girls out there. Never settle and never stay with one that doesn't make you happy or treat you right.
Get tha butter and whip up a strong ass batch of brownies and be positive. I know it sounds cheesy but it is true. Just be happy and you life will start to get better. Just remember you are you. And they are trash. You are a very special person and you need to believe and remember that. If they want to be low life people let them do it and let the reap the bad karma that goes with being an asshole