Difference between ようか・まいか and ようが・まいが

Question

So I'm cramming for the N1 test next week and doing grammar exercises in the 日本語パワードリル book. I come across the following question and felt fairly confident in my answer:

友人に真実を_________　悩んでいる。

１　告げようか告げまいか ２　告げようと告げまいと ３　告げようが告げまいが ４　告げようとどうしようと

Two answers, ２ and 4, I discounted immediately. I remembered the ようが・まいが grammar as meaning "whether or not", so went for that. With the English meaning "I am worrying whether or not to tell my friend the truth".

However the answer is ようか・まいか. Both have the simplistic English meaning as being "whether or not", so I am wondering what is the nuance that I am missing out on?

Is it to do with the 悩んでいる part? Is ようが・まいが more of a "regardless of whether A or B" and ようか・まいか is more of a "debating whether to A or B"? Is the latter always used when you're thinking/wondering/worrying etc?

Answer 1

The important difference is that for the よう[が/と]～まい[が/と] pattern, the thing that follows doesn't depend on the verb. For example if you were to say

友人に病気の真実を告げよう[が/と]告げまい[が/と]、病気が治るわけではない。

it would be fine. Telling your friend the truth behind your disease has no impact on if you will recover from the disease or not.

In contrast, with the ようか～まいか pattern, you are considering to do or to not do the verb. And what follows typically further shows that deliberation with something such as 悩む. Thus, it's the most appropriate choice here.

Answer 2

Is ようが・まいが more of a "regardless of whether A or B" and ようか・まいか is more of a "debating whether to A or B"?

Yes!

Is the latter always used when you're thinking/wondering/worrying etc?

Yes.
The former doesn't mean "(I'm thinking/wondering/worrying) whether or not."

I agree with the sentence below from What particles can be used in the ～よう〇　～まい〇 pattern?

…ようか…まいか and …ようが…まいが have different meanings. The fact that they have the same English translation “whether … or not” is a coincidence.

Edited: to make words correspond to the question