Is it of grave matter to admit to yourself that in a hypothetical situation, you would commit a mortal sin? Is this considered to be the same as planning a mortal sin? I think it is, but is it?
Not sure why you would dwell on a decision to commit a mortal sin. If it’s an unbidden thought, let it go. If you obsess over it, you may want to speak to your priest. It could be a grave matter. God Bless you and may He free you from excessive anxieties.
A priest told me once that we can’t help the thoughts that pop into our head.
It’s acting on them that is sinful.
Are you just admitting a weakness you have? We all should recognize our human weaknesses and try to develop virtues to counter-act those.This is not sinful.
Or are you actually wishing to sin? This is sinful.
Talk to a priest about this…
(I personally do not believe that you’ve sinned at all, but it always is good to ask a priest…)