First things first Rabbit, it is not you, please do not think this is your fault, it isnt. You reacted as any normal partner would when their SO becomes distant, angry and cold - our first thoughts do not turn to a mood disorder, but to the most common cause of grief in a relationship, infidelity. It is not your fault that this is what your thoughts first turned to. Second, breathe and breathe again, you need to start focusing on your own health and wellbeing, for the moment he has taken himself out of the equation and so you have no immediate access to what is going on. Keep in touch with family and friends, dont lose sight of the other relationships in your life that are important to you. This illness is all consuming, its like a black hole that will suck in everything and everyone around it, so you have to look after yourself right now. It is good that you have a therapist, do not be afraid to share all that is going on with your therapist, it is important that you have a professional, objective view of what is going on and they will be well placed to advise you on what strategies are good for you and your wellbeing. If you havent done so already, then read Anne's books as a starting point and then educate yourself as best you can about what it is you are dealing with. You dont mention if he has been diagnosed or is in treatment of any kind, if he is, then that is a good thing. If not, then perhaps a family member maybe able to persuade him to see a professional and get some help,
good luck,
hugs,
Erin