Hi OP,
God I could write you a novel about this! There is a great book (picture book!) about depression written for people whose partner is depressed... I will try and find the link for you, it's about a blue dog following you around all the time.
I am also the depressive one in my relationship, and god, if I can reassure you of anything, it's that depression absolutely, wholly, completely and unequivocally makes you feel like you don't love your partner. Or your children, your job, your pets, your house, your meals, your hobbies, anything.
It makes me mad that the term depression gets bandied around so flippantly. When you are truly depressed, you are just enveloped in the most horrific and overwhelming cloud of hopelessness. It's so so awful and I know it is equally awful in a different way to my husband as I just detach from him and from life.
Please read about it, and try and be patient. I know it's hard. I always try to say its like a broken leg; depression is a medical issue which takes time to heal. No one should expect you to walk around with a broken leg, and no one should expect you to feel normal or be rational when you are having a depressive episode.
Your husband is doing all te right things, and combining drugs with talk therapy is a great way forward. Drugs take about six weeks to start working, they sometimes make it worse before they start to improve it, and sometimes it does take a few trials of different drugs before a good one is found.
I would recommend regular gentle exercise, no alcohol, and a diet heavy in fish and complex carbohydrates. Also, acupuncture is so, so, so helpful. So is gentle yoga.
Good luck, and I know it's hard to believe, but as much as you must believe this is not you, you must also believe this is not him. Depression is like the cloak of doom!