I can feel your pain
Something you say when you know exactly what someone's going through, like when they're stuck in a bad relationship and you say 'Yeah, I was stuck in a bad relationship and I felt like my brain was being tortured.'
My friend is stuck in a bad relationship and I told her, 'I can feel your pain, I was stuck in a bad relationship and I felt like my brain was on fire.'
My brother got dumped by his girlfriend and I said, 'I can feel your pain, I got dumped and I cried so hard I could’ve drowned a dog.'
My cousin is stuck in a terrible relationship and I told her, 'I can feel your pain, I was stuck in one and I felt like my soul was being dragged through a mud pit.'