The narcissistic tendencies are not uncommon with a MLCr.... infact telling a therapist how your H/W is currently behaiving it would be a very simple and logical label to place on them from the outside looking in. Problem with labeling them a Narc is the fact ... its not really true otherwise you most likely would not have been married to them for 15-20-25 years right? Take my 25+ year relationship ... currently yes she has some very strong Narc tendencies but she was never that way prior to BD, sure there was some selfishness here and there, things she seen differently than I did but I would not have tossed out a Narc label on her 10 years ago. One does not become a Narc at the drop of a hat.
Truth is, your H lacks compassion and empathy at this moment because there is so much going through his brain he is not capable of these emotions right now. Dealing with them day in and day out can be exhausting, so you have to arrive at a detachment level where it no longer drains you. You and your reactions are the only things within your control ... you can not make him feel this or that, say this or that, do this or that. You must get to the point where you allow him to go through his journey without your help .... and as far as parenting goes I am here to tell you that the quicker you become both parents the better off you and your kid(s) will be.
