Hi this is very tough and I sympathy but he has depression. The symptoms and the moods swings show it. You need to broach it. Very carefully and cautiously. He may not be ready to open up or admit it yet.
Like the others have said its not your fault. The others have alrady made excellent points so there is very little to add.
I know you said you don't want a break up because you are emotionally involved with this guy.
BUT
You need to ask yourself and answer honestly . Do you really want to spend the rest of your life with this guy who is mentally abusing you ? Unless he changes it isn't going to get any better is it ?
And thats where I will leave it .
Gentle giant wrote:
Hi this is very tough and I sympathy but he has depression. The symptoms and the moods swings show it. You need to broach it. Very carefully and cautiously. He may not be ready to open up or admit it yet.
What symptoms of depressions are you seeing in this? Can you explain it to me please? :) I dis not see any sign of depression pon first reading but maybe I was distracted by something else, and I'm curious about it
I think gentle giant may be spot on, the distance, the intense emotion, the swing between I have experience of this and it was/is depression, the worst thing is until they acknowledge there is an issue treatment cannot begin effectively and this can take many years (not a pleasant journey)
I'm not a professional, nor do I know enough about your partner, so I will not make any assumptions about his mental state.
I will however say that, though I always advocate patience and understanding when it comes to mental health, it is not a get out of jail free card. Mental illness does not excuse abuse. It does not exempt you from being considerate of the people around you.
I understand you said breaking up isn't an option because you still love him, but as others have said, you should question if love is really enough, and maybe even if he really does love you, if he's making you feel "limited" 30% of the time. A partner should be there to support you, and though that doesn't mean they should never criticise you, it does mean that it should be done in a respecting and mutual manner.
I've been in a similar relationship in the past, so I understand that it can be hard to see that someone you're very invested in emotionally and have spent so much time with isn't good for you. If you really don't feel like a break up is the right thing for you maybe try and reach out to people in your life, or see if there's events around you that you're interested in where you could meet people, people are often a lot more friendly and open to being supportive than one might think and if you surround yourself with other people, especially ones who are kind and supportive, it may help you gauge if your partner is treating you right.
Hi and like everyone here has said you need to reivaluate your relationship with this person who is very slowly strangling you , you have to make yourself the biggest priority and make yourself stronger .this guy is bad news .....I hope you can sort this out for yourself 
I really, really feel for you. There is nothing about this situation that is nice or easy to resolve.
I know you have asked people not to suggest leaving, because that is not an option. Is it not an option because you love him and want to make it work, or not and option because of other circumstances? If it is the latter, then someway, somehow it could be an option if that was what you felt was best for you. However if you want to find ways to make it work and ways to help him resolve his attitude towards you then support for him and for yourself will be a must.
Have you consider writing some of your thoughts down about his behaviour makes you feel, and how you would like things to be? Sometimes when we are talking people don;t always hear us in the way we would like, and things can become heated and it becomes much easier to say hurtful things. Sometimes a well worded letter can be easier for people to digest.
I appreciate that he helped you get through your depression, but if his current behaviour has landed you in A&E due anxiety that severe, he is really undoing and of the good he did. Sometimes people who help us through bad times or out of personal diffculties can become so important to our sense of self that it's hard to imagine being right or well without them. But that doesn't mean they can treat people badly. And whether or not he's sweet and nice 70% of the time or not, the rest of his behaviour is terrible.
He may well have some of the issues that other people have mentioned, I'm not a mental health professional so wouldn't like to comment. But even if he does, as some else said that is not reason enough to be eomtionally abusive.
I would definitely think that couples therapy would be a good start, but sounds like individual therapies might not be a bad idea either. Even if he won't go maybe you could look into some for yourself, it may give you the support your need for you anxiety to make you feel strong enough to deal with whatever the future brings.
Good luck ith everything, and I do hope you've had a chance to read through all the replies.