① Something is killing me
非常难受

It's killing me that I'm not gonna see my girlfriend for a year.
一年见不到我女友就好像要杀了我。

My work is killing me.
我的工作让我很难受。

My boss is killing me.
我的老板让我很难受。

My shoes are killing me.
我的鞋让我很不舒服。

② It's tearing me up inside
柔肠寸断/让我难受

This breakup is tearing me up inside. I don't know if I'll ever be happy.
这个分手让我伤心欲绝，我不知道我还能不能快乐起来了。

③ I'm dying on the inside
内心灰暗了、受折磨、伤心欲绝

Harry looks happy but he's dying on the inside. The divorce really hit him hard.
Harry看起来很开心，但其实他伤心极了。他的离婚给了他很大的打击。

Hit someone hard
给人沉重的打击

④ I can't stop thinking about it
满脑子都是、纠结、挥之不去

I can't stop thinking about her.
我总是想她。

I can't stop thinking about work.
我满脑子都是工作。

I can't stop thinking about math.
我满脑子都是数学。

⑤ It's on my mind all the time
满脑子都是、纠结、挥之不去

What he said is on my mind all the time. I can't believe that's how he feels about me.
他说的话我一直挥之不去，我无法相信他是这么看待我的。

I can't stop thinking about what he just said.
他说的话我一直挥之不去。

⑥ It's keeping me up at night
让人失眠、辗转反侧

Our startup is keeping me up at night.
我们的创业公司让我辗转反侧。

My relationship troubles with Rick is keeping me up at night.
我和Rick的情感问题让我无法入眠。

⑦ I'm losing sleep over it
失眠、辗转反侧

My best friend has been losing sleep over his financial situation lately.
最近我最好的朋友总因为经济问题失眠。