From my point of view MLC is different from a breakdown ... a friend had a breakdown and was more or less unable to function at all, didn't get out of bed, didn't interact with anyone.
My H is more suffering from delusions, and schizophrenia, he has a dual life, when he is here, he says he is unhappy with his life and often cries when he has to leave, he doesn't know how to relate to his children and says he has no purpose in life. However, he often goes out on his motorbike, talks to strangers easily, laughs, stays out late and drinks, and has recently I suspect got back with OW for sex. All those things are his other life ... he thinks he deserves to have a fun filled life. He cares not how this damages his children, and how it hurts anybody else. He has delusions that everything is just fine with his left behind family, kids get over it, its not important. He isn't having a breakdown, in some ways I wish he was, it would be easier for us to deal with and understand.