Dear Madge
I would suggest that it is not always possible to ‘act normal’ and ‘pretending’ can become very stressful, so don’t put yourself under more pressure than you can cope with.
Of course, you have to be very mindful of the ***** of your family and you have to be wise about sharing things – not everyone will understand or know how to support you wisely.  But have you got someone you can really trust?  It is not always wise to ‘spill everything’, but is there someone close that could listen to you while you just explain in outline that you are going through a really tough time and may appear less in control etc?  Some*****, just knowing that someone else recognizes that you are really struggling can give you some relief.
Have you got anyone who can help a little with the children?  Just so you get a space to think about yourself.
If you are feeling very alone, I fear this may not be helpful, but I hear your pain in that post – a sort of desperation and want to encourage you to reach out and receive any useful support you can access. 
Compartmentalising is not a long-term solution, but I am sure it is a temporary survival technique for many of us – you probably CAN do it in your professional life, as I note that you are a therapist;  maybe a silly idea, but would it help (temporarily, of course) to think of your situation as that of a client?  Just to get through some of the crazy *****?
Ignore all this if it does not help – you are being thought about and cared for, even though it is only in the ‘virtual’ world.
MoniqueKeep hope alive.