I will speak in general about full consent, also called full deliberation, needed as one of the conditions for a sin to be an actual mortal sin. I’m not speaking about your particular case, since I have no knowledge on that point.
Three elements together are needed for an act to be an actual mortal sin: (1) full knowledge (that the act is gravely immoral), (2) full consent (i.e. resolve, deliberation, choice), (3) and the matter of the act must be gravely immoral. The matter of the act is everything pertaining to the morality of the act, in all three fonts, other than consent and knowledge. Actual sin is a knowingly chosen immoral act. Actual mortal sin is a knowingly chosen immoral act in which the knowledge is full, the choice is full, and the immorality is grave (in a sense, full).
“And when through sin, the soul commits a disorder that reaches the point of turning away from its ultimate end, God, to which it is bound by charity, then the sin is mortal; on the other hand, whenever the disorder does not reach the point of a turning away from God, the sin is venial. For this reason venial sin does not deprive the sinner of sanctifying grace, friendship with God, charity and therefore eternal happiness, whereas just such a deprivation is precisely the consequence of mortal sin.”
(Pope John Paul II, Reconciliation and Penance, n. 17; he cites St. Thomas Aquinas, Summa Theologica, I-II, Q. 72, A. 5.)
There are a number of factors that might affect the knowledge or free choice of a sinful act, so as to increase or decrease culpability. The following are some examples of various factors that may reduce the culpability of a knowing choice. This is not an exhaustive list, but only select examples.
Physical impairments to the brain reduce culpability if either the ability to understand the morality of a choice, or the ability to freely choose, are reduced. Examples would include any injury, illness, or congenital problem that substantially affects mental functioning, as well as any type of intoxication (legal or illegal drugs, or alcohol). This reduction in knowledge and free choice does not affect knowingly chosen acts prior to intoxication, including the knowing choice to become intoxicated.
Psychological limitations reduce culpability if either the ability to understand the morality of a choice, or the ability to freely choose, are reduced. Examples would include psychological problems (transient or chronic), such as anxiety, depression, addiction, post-traumatic stress disorder, schizophrenia, or psychosis. Even when a psychological problem is not a diagnosable mental illness, there may be substantial reduction in culpability. Examples would include: being abused as a child, being fearful because of some serious threat or danger, being oppressed by chronic pain or chronic stress. Examples of psychological limitations would also include factors due to age: the very young, because of limited ability to understand right from wrong, and the very old, because of decreased mental functioning with changes to the brain in old age.
But while psychological factors can reduce culpability, a minor reduction in culpability does not cause an objective mortal sin to be anything other than an actual mortal sin. Only a substantial reduction in the exercise of free will, or in the knowledge of the grave immorality of the act, can cause an objective mortal sin to be less than an actual mortal sin.
