<human>: 4 years ago I met my s.o. online.  We easily became friends and 2yrs ago we moved in together.  I instantly fell in love with him and he fell in love with me.  We match up on so many levels and were very comfortable with each other from the beginning.

A year ago, before he had told me he loved me back, I had sex with someone else, in our apartment.  At this point we were not together, but it was a very bad decision on my part.  I had sex with his coworker, in our apartment, while he was outside.  

It's been a year but it still bothers him from time to time.  

During this year we have taken steps to improve our relationship and be better to each other and show we care.  We were pretty much living as a married couple, just without the official label of a relationship

A few months ago we sat down and decided to make our relationship official and to openly commit to each other.  Neither of us have seen anyone else in this time span, aside from the one day stand.

We both have our issues, we both have been abused sexually, we both have been abandoned, and we both are very understanding with each other.  

He is very insecure about himself though, his body, his age, his weight, etc.  He is not controlling in any way, but I know he gets jealous and immature if I've got a male friend over when he isn't home.

How can I help him understand I will not make the same mistake twice?
I love this man very much and I know he loves me as well, else he would not try so hard with me and be as compassionate as he is.

Can you condense the text into a few key points?
<bot>: I had sex with someone else before our relationship started and broke his heart, we are working to fix it and I need some advice on how to make him understand he is worth a lot more to me than he thinks he is.