Roman Catholic theology is leading you astray on this issue.
In the passage above Jesus does not make any allowance for your positions.
He makes it clear our thought life, in this case about adultery, is equal to the actual physical act itself.
It is either sin or it is not.
Jesus says it is.
This is where the Roman Catholic false doctrine of mortal and venial sins leads the Roman Catholic astray.
I've had too many conversations with your fellow Roman Catholics, and probably you as well, on this issue to know Rome views the thinking about adultery as being different than the physical act.
I agree the earthly consequences are different. If you lust after another woman (or dude if you are a gal), your spouse may never know.
However, God knows and that's what really matters.
Our thought about adultery, or stealing, or murder, etc....even for a moment condemns us.
It's these thoughts we're sometimes not even aware of that condemn us. It shows how utterly impossible it is to be "good enough" to get into Heaven on our own merits.
As I've said before, IF I were a Roman Catholic I'd never let the priest out of my sight. I'd be confessing every hour on the hour....just to be sure.
Fortunately, Christianity teaches something different than Roman Catholicism.
We we profess our faith in Christ He wipes away all of our sins. He nails them to the cross.
13When you were dead in your transgressions and the uncircumcision of your flesh, He made you alive together with Him, having forgiven us all our transgressions, 14having canceled out the certificate of debt consisting of decrees against us, which was hostile to us; and He has taken it out of the way, having nailed it to the cross. Colossians 2:13-14 NASB
In summary, people REALLY don’t like it when their sins are pointed out and condemned.
Not even in general terms.
They don’t even like being reminded.
I made an enemy for life when I pointed out that someone saying, “I’m not so bad; I haven’t actually killed people, so I must be fine in God’s sight, yes?” is still under God’s condemnation.
He threw a FIT and started spreading outright lies saying that I told people that all veterans are going to Hell, then after that spent over a year trying to financially and psychologically ruin me while also trying to get me excommunicated.