Gracey -
I may be way off base here and this is only my opinion.
All of this is not your fault. You already know that your husband cheated on you once. From your posts about him, it doesn't seem like that issue has ever completely been resolved. I know you posted once that he was threatening to do it again.
You may have issues from the past that are coming into play. BUT, your H has done his share of damage to your relationship. You H has not helped you to get over your insecurities from the past - he's confirmed them.
Don't take on all of this guilt. Recognize the issue and take steps to resolve it but don't make yourself feel bad because of your feelings.
Hugs - L