Infidelity Support Group
Any relationship in which one partner engages willfully in sexual relations with another outside of the partnership is considered to have experienced infidelity. This breach of trust is often traumatizing for the faithful partner as well as the relationship, and support is often needed to heal emotionally and to decide whether or not the relationship should continue after...
I think you have to come to the realization that he is cheating while he is away. You have all the proof you need, and he's showing all the signs and symptoms of a cheating spouse: shows little remorse, leaves therapy, locks his phone, changes passwords, uses the silent treatment, responds with the angry-if-you-ask-him treatment so you stop prying, all point to a cheater in action.
He doesn't have a sex drive for you because he's getting it elsewhere and he's probably formed a couple of sexually deviant behaviours from camming. I believe it's time to visit a lawyer for a consultation to find out what your rights are. Do you have family close by you can lean on? If so, go to them, tell them, let them help you, because you're going to need help getting through the devastation of infidelity.
Just know that nothing you've done has anything to do with his dalliances. Not hormonal changes, not gaining weight, nothing. This is all his own doing. You have been a loyal and faithful wife and mother. Don't ever let him make you believe that anything you've done or not done, has anything to do with his infidelity. I would also seek the help of a therapist for yourself, to help you understand that this has nothing to do with you. It will also help you heal in a way you can understand your emotions.
I wish you well.