I found this site very useful after my DH's affair 4 yrs ago - we are still together, it has not been an easy path to walk.
His affair lasted about 3 months and was a classic mid life affair see Romantic Infidelity here. He moved in with the OW for about six weeks (I had no idea what was going on, he had seemed to have had a personality transplant, the DCs were traumatised, I was traumatised, the business was being neglected/compromised - in effect he had pressed the self destruct button and was taking me and the DCs with him).
He moved in with parents for about 4/5 months and in that time we went to Relate. We both made the decision that we needed to try and repair the marriage. I needed to be able to look my DCs in the eye and say I did all I could IYSWIM. We owed it to our DCs to try and establish a good solid relationship and family. If my DH was not willing to put the work in and be prepared to walk the walk then I would have called it a day.
One of the most important things, if no the most important thing, I did was to re access my life and what I wanted from it. I had given my all the the DCs and DH and lost myself along the way. Spoil yourself, take long baths, treat yourself to new clothes, hair style etc, take up a long forgotten hobby again (I took up horse riding after a 20 year break). You need to be selfish and put your needs first and you also need to put the needs of the marriage high on the list too.
You also need to surround yourself with friends of the marriage (DH distanced himself from certain people whose mindset and behaviour condoned infidelity IYSWIM).
During our separation, DH arranged date nights for us, weekends away (our families knew about the affair so were more than willing to babysit to help us repair the marriage). He also did his fair share of the childcare, taking the DCs to school, doing bath and bedtimes even if he didn't stay. He worked like a Trojan at his business to repair the damage there as well. In fact he completely turned himself around - if he hadn't had done this then the marriage would not have survived.
After about two years, he took himself to individual counselling again to try and understand himself more - he has been damaged from his very dysfunctional childhood.
Four years on we do have a better marriage, we both understand what we both need from each other and from ourselves. The innocence of the marriage is gone but we have a more adult relationship now if that makes sense.
Above all one day at a time and be kind to yourself, do not expect too much from yourself.
Good luck.