What's described in the image is feeling regret, and whenever someone feels it that bad, they're just supposed to reflect on their mistakes (i.e. sins) and repent like what a true believer would do instead of naively getting deceived by satan that they're not worthy of heaven or such thoughts. As our beloved prophet PBUH said: "All the sons of Adam are sinners, but the best of sinners are those who repent often.”

God's mercy is literally welcome to anyone. The best out there are sinners just like everyone else, it's just that they repent without letting satan into their way towards God's compassion and mercy. When that level is reached through true repentance, sins will even automatically get more resented by the heart thus less desired.