You really have to differentiate between the guilt that comes from depression and genuine guilt which comes from doing bad things - immoral things more so than illegal.
Then perhaps, you have a mixture of both forms.
Either way, if what you have done is wicked and evil (murder, rape and so on) then hopefully you'd turn yourself in.
Depression is like an amplifier for negative things so its little wonder guilt would get dragged into it. Why not? It makes sense really that depression would 'hijack' a few little guilts or regrets and leave us feeling like we are the worse son or daughter, mother or lover or carer in the world.
It's really just a trick of the mind. Like a panic attack. I mean, ever feel panic in a crowd, or shop and feel that old flight or fight instinct? You know its a trick of the mind as there is no impending danger you need to fight or run from.
Also, ever have a feeling, just before you drop off to sleep, that makes you feel like you are falling from a great height? Again its a sign the mind makes us feel some things which are not real. This guilt is just one of those moments - extended, because guilt is not some instant feeling that pops up and dissipates.
As for feeling bad about your partner icemaiden - its natural even if you done all you could to focus on the ever present failings we ALL HAVE. I know about caring and have seen people who have cared for terminally ill people. Sometimes people want more than we can give - someone who is very ill might only want close ones to care for them - but if your the only one really there then you exhaust yourself. If you made some bad judgement towards the end - it was just down to a traumatic and likely exhausting period of a few months prior to you not being able to carry on till the end. You done what you could - his pain is now over and you should pray for him if you believe, pray for yourself also. When people die there is often a time when even big families with lots of people to care might not be able to pull off what seemed to do perhaps almost single handed. I'm guessing others might feel guilt in that case.
Even parents of terminally ill children generally always use the hospice because there they get 24 hr care, love and attention. Pain relief needs that level of care sometimes.
Guilt is like a cancer. Instead of cells multiplying its the thoughts that multiply. Just one thought will pop up at first. You've let someone down maybe - made a big mistake - maybe you lived a genuinely bad life. You think you're 'no good' and that's all you need for guilt to multiply and drag up EVERY negative thought that the darkness of your mind can muster up.
You got to take action against this - become angry about it because its a real KILLJOY. I mean depression, by itself, it's not too bad. Guilt is worse because it mimics a very real emotion in us - in fact perhaps something that makes us who we are. After all - if we judge a person by anything we will judge them on their capacity to have some moral code.
Accept your depression. We have no choice there and depending how long you've had it then maybe its just a part of you. But guilt - if you want to determine whether or not you are really guilty of something - just write down on paper the things that were so wrong. For most people its just the usual things - we make mistakes - we feel bad about them then we rectify the behaviour that caused the mistake.
First off you need to ask whether you have a moral code.
Then assess whether it ties in with common sense.
Given many here will actually feel like they need to die because of some imagined guilt - its time to realise it is an imposter for the real thing. Real guilt is a recognition of wrong - genuine shame is a wonderful thing IF that sense of shame of guilt is a wake up call.
If your guilt, on the other hand, is some kind of thought process of negativity - the recurring theme that holds back your life - then its false guilt - and if you disagree then that's only natural also. Your so convinced by the authenticity of the feeling because its what you wake up to and what you go to bed thinking about.
Rest assured, what you feel is not always how it is. We can become convinced of the craziest of notions sometimes.
The main thing you need to do (if you have not) is to obviously seek some help and talk to people about this horrible illness. Guilt is sometimes part and parcel of depression, to a greater or lesser degree it it is perhaps the root of depression. I think everyone who gets depressed must feel guilt eventually. Come to think of it - is there anyone with depression who does not feel guilty about something?
The worse guilt is the sort people kill themselves for. This can be genuine, I know someone evil who killed themselves. That said, almost everyone I know who died in a variety of suicides, all felt some kind of guilt. Guilt for not being able to cope with the kids, guilt over feeling not good enough, guilt over being a burden. Sadly, many have died with this persistent emotion gnawing away inside.
But you got to know it really is just part of the illness - the condition.
If you were truly a bad person, trust me, you would not feel an ounce of guilt over actual crimes and certainly not waste a second of your time dwelling on how you may have made others feel bad.
I feel some genuine guilt about not caring enough for family in my youth and reckless days of being a young man. I counter that by doing nice things now and being the one who can hopefully care for them up until a point were they need professional help, hospital stays and so on.
If you have made mistakes in the past - its part of life. We make a trade off by recognising our mistakes of the past and using our leant wisdom as and when we can help in the here and now. This way, we can maybe feel a little bit good about ourselves.
Get help if you have not done so. Help others once you feel like your guilt is just like that which most people will carry around.
Good luck!