It will take you a long time because you have been together a long time. Besides that, you are still living together with no immediate plans to physically separate. It will be impossible to move on until one of you has literally moved on/out.
I feel sorry for him, too. If you have had one foot out the door for several years, whatever your relationship was previous to the affair is his normal even if it was not a normal relationship. Besides that, if you have never talked to him abt your unhappiness and/or he didn't really understand what you were saying or took you seriously, this is a huge emotional bombshell to have to deal with and work through in a relatively short amount of time. You had years to fall out of love and mourn the death of your relationship; it's only been a few weeks for him. He needs time and patience and love.
However you feel abt him now, he is the father of your children and your spouse. You really should try to reach out to him and see what he needs and then try to make that happen. Maybe he needs some more physical space. Maybe he wants to talk abt it. Maybe he just wants a heartfelt apology. I don't know. He might not know. You could let him know, though, that you want to make things right/better by being sensitive to his needs as he works through losing such a giant part of his life without any warning and without getting to choose to lose it.
You don't have to get back together with him but you could make these next few/last weeks with him something you can be proud to be a part of.