I'm in need of advice. Please?

Are any of you guys the nice person in life, whose always there to help, and just overall sweet? Well I am that person in my town, but I’m scared. Really scared. I keep feeling like I am acting rude and inconsiderate. I told my friend I was going to meet them for lunch today, but my mom kept asking me to carry in groceries, and to continue putting them in the fridge. I finally said I needed to go, and she said I was acting rude. Also during today, I was with my friends. One of them wanted to go outside, but me and my other friend wanted to stay. Then later, I felt like going outside, but they were playing video games. I asked if we could go out and that friend said “JULIA! Ugh. Why do you have to be so selfish only want to go when YOU want too?” and also said I was being bitchy. Bitch. I CAN’T GET THAT WORD OUT OF MY HEAD, AND IT’S DRIVING ME NUTS. WHAT HAVE I DONE!? I am NOT THAT PERSON. I’m the one who will giggle when someone says to lick a tree, not become obnoxious and unwanted. Guys, I need help, what’s happening to me?