Am I a horrible person for forgetting? I feel horrible

Even though my immediate family (Mom, twin sister, and I not brother since he can afford the Acura and eat out every night) is stuggling badly, I still give money (no less than a dollar) to that mentally challenge homeless man whenever I go downtown with my sister to GSU. Today, I forgot that dollar. I knew I had it in the car that we all share/drive, but forgot it. I tried to avoid seeing the older mentally challenged guy while I was down there this morning but I saw him in his not normal spot near the Five Point’s Train Station. I couldn’t walk past him so I walked a little further down the street and crossed somewhere else and almost got hit by a car. That’s how upset I was, upset that I forgot to help someone else out like I usually do. What makes it worse it that Thanksgiving is Thursday. I suggested to my mom that I could make a few meals and take them to homeless people downtown on Wednesday but…she said no and we don’t have gas and the money for gas. Our car is almost at the line before the dingger that tells you “Hey! You need to be thinking about getting gas!” That’s all we have to last us the remainder of November until the middle of December when our mother gets her Social Security money (medical reasons). So with that said, do you think it was wrong of me and selfish of me to forget the dollar that I always give that man?