I'm sorry for your pain and confusion. I hope that you can find help and companionship here.
For your question about whether it's MLC, it does seem to have a lot of the hallmarks. Was there a particular episode which triggered his changes--often there is a health scare, death or other trauma which precipitates the slide into a MLC depression? This causes the MLCer to change overnight from loving to angry/uncaring/self-absorbed, etc. Otherwise, read through some of the threads Cadet has suggested--there's wonderful and very helpful stuff there.
Your situation is a little unusual in that your H is spending so much time with his daughter (and perhaps trying to impress her mother, too?). This made me wonder whether his crisis began earlier, with the break-up of that relationship? Trying to make up for lost time with his daughter, etc, in some ways seems like a positive and necessary thing to do--if only he could do it in a way which included you, rather than excluding and blaming you.
Try, at this point, to do everything you can to nurture and take care of yourself.
