fix:
Well, mortal sin is mortal sin. No sanctifying grace is no sanctifying grace.
But some mortal sins are graver than others. This is noted in the Catechism in a few places such as these:
2356 *Rape *is the forcible violation of the sexual intimacy of another person. It does injury to justice and charity. Rape deeply wounds the respect, freedom, and physical and moral integrity to which every person has a right. It causes grave damage that can mark the victim for life. It is always an intrinsically evil act.
Graver still is the rape of children committed by parents (incest) or those responsible for the education of the children entrusted to them."
Rape in general and rape of children commmitted by parents are both mortal sins but the Catechism notes that the latter is “graver” than the former.
1858
The gravity of sins is more or less great: murder is graver than theft. One must also take into account who is wronged:
violence against parents is in itself graver than violence against a stranger.
Any sin, including mortal sins, can thus be classified as more or less grave than any other sin.
Homosexuality is a graver sin than fornication or adultery. But it is not the gravest sexual sin. Bestiality would be the gravest sexual sin.
I know that those who are afflicted with disordered homosexual desires are called to Christian chastity, but I don’t think they can really be fully chaste until they shed themselves of these disordered desires because it seems to me that desiring to commit a sin is itself a sin, an “adultery of the heart” which Jesus likened to the act of “adultery” itself. If it’s not a desire but just an emotional inclination, I still think they can’t be completely chaste while having these disordered emotional inclinations since the Catechism teaches:
1770 Moral perfection consists in man’s being moved to the good
not by his will alone, but also by his sensitive appetite, as in the words of the psalm: “My heart and flesh sing for joy to the living God.”
Of course most heterosexuals, aside from the Saints, are far from moral perfection too.