You (and perhaps with the help of your confessor) will need to judge. It is hard to say from what you said…for when you say you had the thought for the purpose of arousal …well was that done with full knowledge and deliberate consent…and then you later started resisting? Or was it that the though started…and you were attracted but started resisting it when one realized what was happening???
It may be something to simply bring to confession and note what you noted here.
In any case…make an act of perfect contrition and keep close to Jesus in Prayer.
From Compendium issued by Pope Benedict XVI:
- When does one commit a mortal sin?
1855-1861
1874
One commits a mortal sin when there are simultaneously present: grave matter, full knowledge, and deliberate consent. This sin destroys charity in us, deprives us of sanctifying grace, and, if unrepented, leads us to the eternal death of hell. It can be forgiven in the ordinary way by means of the sacraments of Baptism and of Penance or Reconciliation.
- When does one commit a venial sin?
1862-1864
1875
One commits a venial sin, which is essentially different from a mortal sin, when the matter involved is less serious or, even if it is grave, when full knowledge or complete consent are absent. Venial sin does not break the covenant with God but it weakens charity and manifests a disordered affection for created goods. It impedes the progress of a soul in the exercise of the virtues and in the practice of moral good. It merits temporal punishment which purifies.
(from an past post of mine)
Of course we need to reasonably avoid temptation we know will be a problem for us…that we can reasonablly avoid…now we of course know we can not avoid all…for they are everywhere…but one has to know oneself…and for example know that he needs to not watch a particular movie etc…but even if we do this…there will still be temptations!
Some helpful advice …drawn from Tanquerey (from the 1930’s) (but my words somewhat)
When one is tempted…
Now what are some signs of lack of consent or partial consent…
- We may judge that there has been no consent if in spite of the suggestion and the instinctive pleasure …we experience disgust or not happy we are tempted…or we struggle not to be overcome…it we are horrified at the evil…if we turn to God in prayer…(and of course do not later consent)
- If one does not reject the temptation as soon as one realizes it it is dangerous for one…this is a fault against prudence …
- If one momentarily hesitates… but then does not want to offend God etc…(does not want to commit a mortal sin etc)…and after that moment of hesitation repels the temptation–again there is a venial sin of imprudence.
- If one resists the temptation in a half-hearted way…one does resist but weakly…or slow way …but in the end rejects the temptation…there would be it seems half-consent…thus a venial sin.
If one completely consents…to something that is grave matter with full knowledge…then one committed a mortal sin.