I NEED to be able to forgive him

My husband has done some terrible things over the years (not cheat) and now he is trying his very best to mend the broken heart that comes with it... You probably all recognize the stuff out ADHD partners put us through so i wont list everthing but please, how do i forgive and let go??? 

I have already googled my brains out and "just let go" is not working :(