I actually know how you feel. My wife's affair with a coworker began exactly 5 months after we married and I found out less than a month later.
We didn't have a large wedding or anything, it was more a formality than anything. Just us and our daughter down at city hall. We'd been engaged for what seemed like ages but because of how dysfunctional our families are we could never have the lovely family focused wedding we wanted. We waited for certain people to get over themselves (mainly her immediate family) but in the meantime other people died and resentments grew. We just kind of said screw it "lets do this for us". So that day was more to formalize what had already been for years.
I look at pictures of us from that day and we both have the most genuine smiles and loving looks on our faces. We were truly in love. Yet she hated herself, and that's why I'm here.
It sucks really. Our first wedding anniversary comprised of us having a multi-hour conversation about her affair and everything that lead to it. It was an extremely cathartic and necessary conversation for me and considering our lives now was a true step forward for us, but I'm not going to say I envisioned my first wedding anniversary dealing with that when I said "I do" a year prior. We also had a nice night out to a movie and she gave me a photo album of various pictures from our life together with a large section to be filled in in the future (I still really like the symbolism she was going for). She also wrote out and gave me new vows to replace the ones she'd so easily tossed aside. I don't even know if I did anything for her, I think I wrote something but can't even remember. Sadly, that's how important it was to me.
I put much more stock into our relationship anniversary, which is in March. Yet, well, their affair started about a week after our 8th. So... kind of bugs me too now.
You're in early days, and considering how recent your D-Day was and the fact he cheated not long after marriage you're in for a hell of a ride. I don't say that to scare you or cause concern but as wisdom from someone who's been on this particular version of the nasty rollercoaster. I still feel those pangs of grief at a year out when it comes to that. Not even a year married. I at least can look at our years together prior to her breakdown and cheating. Yet still... 5 months and it happened.
Hopefully your husband can dig deep into why he would risk everything after making such a commitment. For my wife actually getting married inadvertently scared the shit out of her without me realizing. I truly loved her, something she could never believe (because of her FOO issues) and there I was committing myself to her forever. Her internal hate and self destructiveness then blew up when a select few events transpired with her family and she decided to blow up her life and make sure I'd leave her for someone better.
Sorry if I'm rambling. Been sick and can't think clearly, but was struck by that similarity between us. Just wanted you to know you're not alone, and how you feel is perfectly normal.
Me: 28 ~ Her (FR2012): 27
ETA: Forgot to mention, I have decided that I do want one thing in the future from her because of all this. When the time feels right, when she thinks it's appropriate and when life is good and we're in a great place together for some extended time I want her to propose to me. I want to eventually renew our vows and "remarry". But I want her to ask me, to win me back fully into the relationship and marriage to the point I am not only comfortable doing so but want to.
Together: 9 years, 2 children
D-Day: April 19, 2012
Surrender to the truth of life.