Hi , I am glad you have updated and that you have been to a Dr and getting some therapy . It is really important that you continue to look after yourself and that will help you have the energy to continue to be the good mum you are .I hope you are also getting some support from friends / family .
I think you are correct that he may be in guilt mode at this point . He may also be demonstrating to the OW what a catch he is , as he is such a good father . She is absolutely delusional , who would want someone who has treated his wife and young family so badly ? You are right to be sceptical about this contact . Take it as a bonus whilst it lasts . You have to lower your expectations of him and if he does contribute that is great .
Use the time he with the kids to recharge / appointments etc
I hope that you have got some legal advice as this is essential as a SAHM . If you find things overwhelming, speak to your solicitor about slowing things down and if doing so would prejudice you in any way .
It does get easier and you will find it is no longer the first thing you think about . You will of course still have to keep in contact due to your children and as you have been together so long and have a family together, your memories are also entwined . This is difficult as I am sure he is the last person you want to see / think about .
I know everyone says it is better to be dignified but we are all human and I found I was angry /sweary / shouty / sarcastic . We are all human .
There is an American website called "Surviving Infidelity " which does have some good info / resources on it .
You have got through the most difficult part and there will continue to be challenges ahead e.g kids birthdays / Christmas / sorting out the finances . You will continue to get stronger and see that you are so much better without him .
I know it may not feel like it at this time , but you are young enough not to let this derail the rest of your and your children lives . It has been tough though and also not what any of us would choose for our children . Whilst statistically we know that a lot of marriages end in divorce , we still do not think it would happen to us . We never expected the person we made our vows to & had a family with , to betray us .
As others have said this is on him not you . Take care .