Don't blame me. I didn't make it worse than it was.
This sentence sounds fine to me, as it looks analogous to another utterance I know to be idiomatic "It's worse than it looks". But I wonder if question words can also be inserted after "than". Does the meaning change in the following sentences?
Don't blame me. I didn't make it worse than what/how it was.
It's worse than how it looks.
Also, it seems to me the past perfect tense here would be more logically/grammatically sound. Is the past perfect needed here? Does it change the meaning?
Don't blame me. I didn't make it worse than it had been.