I have done a lot of things in my life of which I'm not super proud. Granted, I've never killed someone, so logically speaking they could be worse. However when you're talking guilt, oftentimes logic just seems to go out the window. This is frustrating to me, being a fairly intelligent person. If I want to evaluate my life actions, and how they have impacted people and things (and myself), I damn well should be able to apply rational thinking to it.
But instead, I get to contend with things like Society Beliefs that are lodged into my brain. Role expectations. My own sense of self-worth, and how that affects how I internalize things or blame myself possibly unfairly. And I think worstly (yes, that's a word according to me who just typed it, shut up), when you hurt people you love, for whatever reasons.
I think part of guilt can be comparing yourselves to others, and how they have dealt with situations, perhaps similar to yours in some way. It's difficult to remember that everyone is different, and you don't always know their entire story, nor do you know what coping mechanisms they may have in place that you don't. It's easy to beat yourself up, for example, over the fact that you just don't seem to be able to quit smoking*, when all these people you know did it quite easily (it seemed). The fact that you're going through a divorce, and a long drawn-out custody battle, and having to move and dealing with all this stressful shit doesn't even seem to register in your brain as a "oh hey, maybe this is a contributing factor to why it's so difficult." You just compare, and find yourself coming up short and feel guilty about it. Bad brain! Sometimes the most important thing you can do is cut yourself some slack.. realize that you don't have to feel bad for not being able to handle a situation the way you envision you should be able to. Sometimes.. you're just doing the best you can to keep your head above water.
Other times, it's easy to feel guilty for taking actions that are for self-preservation, but at the cost of people you care about. I know for me, it's much easier to allow myself to be hurt, than to see others I care about hurt to spare myself. And so, you suffer, maybe for years, unhappy but hey at least this helps maintain the illusion that everything is alright. Of course, inevitably this just makes you miserable, which then makes everyone around you miserable. But so many times that voice in your head, the Society Says voice, says "You should be thankful! What's wrong with you! Stick it out like a good little trooper!" and you listen, and believe it, and things don't get better. Sometimes, taking action means hurting people in the short-term, but in the long-term they would be much worst hurt because of the cumulative shit that's piling up. You'll be more hurt too. It's so difficult not to entirely take the blame for things that happen, especially relationship-y things. The most difficult part of all this, is not taking action, it's forgiving yourself afterwards for not living up to the unreal expectations in your head, or in others' heads, and for the hurt you had to inflict. It's also learning to forgive others for putting you in that situation, requiring you to make this terrible choice.
The key to all of this, is realizing that this is a slow process, changing how you think and forming new habits of thought where you have more positive self-loops and don't just automatically beat yourself up over things that have happened, that you can't change now. That, and chocolate. Chocolate definitely helps.