forgiveness and mercy for bad sins

I have a question concerning God’s mercy and the extent of it. If I have for all my life been as bad as those who are mentioned in the Talmud as having no share in the world-to-come by virtue of them being extremely evil, would this beautiful verse from Scripture apply to me also in the last moments of my life. Isaiah 1:18-19 Come now, let us debate, says the Lord. If your sins prove to be like crimson, they will become white as snow; if they prove to be as red as crimson dye, they shall become as wool. If you be willing and obey, you shall eat the best of the land. What I mean is if I have been as bad as Achav and in the last hour of my life I have a broken spirit, a broken and crushed heart(Psalm 51:19) and also only do all the good I possibly can, is it still ultimately punish me forever along with the likes of Achav?

True repentance and sincere improvement, turns everything around, even at the last moment. But obviously don't wait for the last minute, because you never know when that is going to be, and you may even miss it! Even more important, it's childish to be good just to avoid punishment. We do good out of identification with the eternal morals and ideals of the Torah, and that applies every day, so it's crazy to wait and miss out on being good!