It's not a game to play.
You'll have to ask someone else about mortal and venial sins. That's not part of my beliefs.
God says that marriage is one man and one woman until death. He also says that sexual acts are shared between the husband and wife only.
That means, not just unmarried homosexual people should refrain from sexual relations with each other but unmarried heterosexual people should refrain also. It also means that married couples shouldn't be having sexual relations with other people outside their marriage. That would be adultery.
It's not a competition with winners and losers.
