Military service can instill a certain sense of comaraderie in people, and it looks like your husband was predisposed to that anyway. It doesn't help that y'all have PCS'd overseas and you probably don't have many people to rely on for friendship and support.
It's no wonder that you are feeling left out and underprioritized in his life.
In answer to your question about letting the events of the past go, you have to CLEAN THE SLATE. What that means is that you and he together must decide to begin anew, and let every transgression of the past fall away. You must release your built-up resentments, and that means BOTH of you. Then you have to remind yourselves DAILY that you chose to forgive.
That's not going to be easy in your case, because the issues still appear to be on-going. He has to be willing to recognize his previous behavior as a problem in order to correct it, and it doesn't sound like he thinks he has one. (And you have to do the same in answer to any issue that he has with you.)
It sounds like your problems are mostly communication problems. I think that if you will both really
listen to one another and then try to meet each other's needs, you'll likely work it all out before it gets worse. Try to repeat and rephrase when you are talking in order to maximize your understanding of the other person's issues. Don't be drawn off topic by issues from the past, and don't try to 'build Rome in a day'!

Tackle one issue at a time.
Good luck, hon.