我累坏了=我很累。I'm very tired.

I am very tired in English ^^ 我很累坏了（wrong） , 我累坏了。（right）

I just say 我很累 pretty much every time. It seems to do the job.

我累了 = I am tired. 我很累 = I am very tired. 我累壞了 = I am extremely tired. see http://www.italki.com/answers/question/156916.htm

There are some similar ways to express the meaning in regards to 'I'm very tired' in Chinese as the below. I am very tired, I'm so tired.--- 我很累。 / 我真的很累。 I am fucking tired. --- 我真他妈的累。/ 我累的不行了。/ 我累趴了。/我累翻了。