What can I do to help my partner stop holding past wrong doings over my head?

Through changed behaviour of these wrong doings. It is pretty difficult to keep crucifying someone over past wrong doings if they no longer do them and are committed to change.

If your partner is holding your past against you, it may be because it deeply affected them and it still does, especially if you didn't apologise. Sometimes an honest discussion about how it made them feel and what you can do to correct it can help move both of you forward. Let them know how it's making you feel and that it's not fair to hold anyone's past against them!

Talk to him kindly, express how it makes you feel and ask him to forgive you and give you a chance to be a better you. Tell him how much you care and how much you are willing to improve to not let the past mistakes happen again. He needs some reassurance, he is just scared because it hurts. At least I think so. :)

I think time heals wounded hearts. Moving on doesn't happen overnight and this is the time that your partner needs you the most. You could give encouraging words humbly telling him that nobody's perfect and that It's okay to make mistakes since mistakes are what teaches us about life and makes ourselves better. I believe that our challenge everyday is to become better than yesterday and everyday is an opportunity to do that. You may also suggest doing activities together to ease him off of his negative thoughts. Helping your partner move on may require patience but consider every step and every effort, may it be little or huge, as progress.

This is a tough one, the key is open communication with your partner. I would think that it would also require address the issue of trust without skirting around it.