Hi,
The very basic approach is to apologise (as stated above)
When apologising they need to be authentic and genuine. Certainly it is obvious when our apologies do not come from a place of genuine remorse and empathy. The words are important in that you need to own your infidelity. You need to own the fact that you have hurt your BS. Using terms like "I’m sorry you feel upset" or "I’m sorry if I hurt you" are poor. Neither of these own the fact that you DID hurt them or that it was YOU who inflicted the hurt. "I am sorry that I hurt you" is better. You will need to know what you did to hurt your BS too and apologise for this.
A good book to read is "How to help your spouse heal from your affair" by Linda MacDonald. A short book but useful.
Also worth noting is that there are no magic words. I came on here seeking those. Each individual BS is different and picking a few lines expressed by a WS on here is not going to help (see genuine above) you need to know your BSs needs and attend to those. Don’t just apologise once or twice and expect that to be it either. Apologies may be needed for years to come if and when you BS triggers. You have to evaluate each and every situation and try to react appropriately each time. We get it wrong and we learn. Hopefully this learning will not come too late.
Do not blame your BS when they trigger. The trauma we have inflicted runs deep and the hurt we have cause can and will come to the surface a lot. When this happens treat your partner with empathy. If like me you lack this, then read and learn quickly. We all have it, but we need to drag it from the recesses of our mind where we have hidden it away. Without empathy without living our BSs reality, we flounder. When we do, and we do, avoiding shame spirals and shame is important. Self loathing is still a selfish act, hard as it is, we still need to focus on our BS.
Your BS is hurting. There are going to be questions that you want to avoid, thoughts that will come to you that you will try to suppress there will be work needed by you to try to understand what you did and why you did it. This work hurts like hell, owning our past hurts like hell. There is no chance, however, of saving your relationship or even yourself without starting this process.
It has been a couple of days since you posted this. I imagine you have other questions or responses to what has been posted up to now. With more information from you, there are WS on here further down this line who can offer support and guidance more than I can. I hope you chose to post again.
WH (50's)
Multiple sexual, emotional and online affairs. Financial infidelity and emotional abuse. Physical abuse and intimidation.
D-days 2003, 2017, multiple d-days and TT through 2018 to 2023. 28 years of destructive and health damaging choice