We're in it together, through thick and thin.
我们同甘共苦，患难与共。
We're family.
我们是一家人。
No matter what your problem is, we are together through thick and thin. We're family.
不过你有什么困难，我们同甘共苦，患难与共。我们是一家人。

No matter what.
不管怎样；无论如何
It implies that no matter what happens, the family is still together with one another.
这意味着无论发生什么事，一家人始终会团结一致。

I've got your back.
我支持你。
Buddy, I know you're short of money； I've got your back. How much do you need?
兄弟，我知道你缺钱。我会支援你的。你需要多少？

It's going to be okay.
会没事的。
Don't worry about your presentation today, it's going to be okay.
别担心今天的演讲，会顺利的。

It will come out in the wash.
事情最终会水落石出；事情最终会过去的
Don't worry about that small issue, friend. It will come out in the wash.
朋友，别担心那件小事。事情最终会水落石出的。