I know how you feel. 我懂得你的心情. I know what you've been through. 我知道你经历过什么苦楚.
I got you. 我懂你的意思了. I dig. 我明白了.
It happened to me on a smaller scale. 同样的事也发生过在我身上, 只是没那么严重. I know what it feels like to hit bottom. 我可以体会跌入深谷的感觉. Thanks for being so understanding. 谢谢你如此体谅人. We are sympathetic. 我们很同情你的处境. 我们深表同情.