Hi Michele, your statements itself suggest that you are done with the relationship but you still want him to be happy when you are gone. This is really nice of you . Well I think his feelings should not be your concern now. Mistakes can be overlooked few times but 3 years was long time for him to learn from his mistakes. Confusions in relationship makes life complicated and it eventually robs you of your happiness.
You said you don’t have feelings for him any more. This itself indicates that you should end this relationship and look forward for a better life where you don’t have to watch your every action in fear of your boyfriend reactions.
I have read a love story probably this might help in reminding you what love actually is.

http://upsohigh.com/in-love-with-memories/

I personally believe that every time love comes in our life, it comes with an expiry date. When you feel that the expiry date of your present love life has reached you should better get going else you will spoil the memories too..Well that’s my perception.