Why is it so hard to forgive yourself for addiction??????????

Over the past month I've been working hard to understand my addiction and now it all comes down to one thing. How do I forgive myself for something that originally was a replacement for something worse. Not only for addiction but for everyday mistakes...... like not wanting to study due to something that has been said in the States as "Senior-itis."

It's my last semester and there are a lot of unknowns which is registering in my head as us it as a trigger for addiction. so I did. And know it comes down to forgiveness yet again.

Any tips from those that have been able to forgive themselves for an addiction?