@iusedtobeasize8
My counsellor said DH’s reasons for the affair were what was lacking in our marriage. In his case he said fun and regular sex
The thing with this is that it's not up to one partner to meet the other's needs. So, if he had unmet needs, it was up to him to get them met, and crucially, he had the option of doing that healthily, within the marriage, by communicating to you what was happening for him, how he was feeling, what changes he would like, etc.
Did he do that, before going and finding someone else?
It wasn't your job to guess his needs, and magically get it all right for him. You were having your own life.
As for childhood trauma... well, it can explain a lot, but it doesn't make inexcusable things excusable. I used to have a very explosive, unpredictable temper, due to childhood trauma. But it didn't make it ok. And I had to deal with it. Childhood trauma doesn't mean you get forgiven for treating people badly, it just explains why you do.