I can feel your pain
When you tell someone you know what they're going through, like when they're mad at their mom and you say 'Yeah, I got yelled at by my mom so hard I thought my ears were on fire.'
My friend got yelled at by his mom and I said, 'I can feel your pain, I got yelled at so hard I thought my ears were going to pop.'
My sister got in trouble for eating all the candy and I told her, 'I can feel your pain, I once ate all the candy and my mom was so mad she screamed.'
My brother got grounded for playing video games all day and I said, 'I can feel your pain, I got grounded and it felt like my life was over.'