Forgiveness is the final form of love. 
--Reinhold Niebuhr

sometimes the person hardest to forgive is yourself. i don't know of any scientific studies that address the consequences of not forgiving yourself, i have read a lot on the subject. boyd k packer  said of forgiving yourself: "often the most difficult part of repentance is to forgive yourself. discouragement is part of that test. do not give up. that brilliant morning of forgiveness will come" on another occasion, elder packer  said, "forgiveness is a powerful spiritual medicine. to extend forgiveness, that soothing balm, to those who have offended you is to heal. and, more difficult yet, when the need is there, forgive yourself!"

remember that if the Lord is willing to forgive us, and he expresses that in scriptures, why should we not forgive ourselves? why should we keep tormenting ourselves for past mistakes if we have done all we can to correct those mistakes? while this is easier said than done, the realization that we aren't forgiving ourselves, but that we need to, is often the first step to forgiveness.