My heart goes out to you as you face the overwhelming struggle that has come with your sister passing.
It's good that you suspect you know why the self harm took place. Knowing why can definitely make things easier in the way of managing that impulse. Can't help but wonder if the self harm led you to feel sadder. The reason I ask relates to my own reasons for doing it when I was much younger and how it led me to feel. By the way, I'm a 70s gal too, born bang on 1970.
While emotions can feel like a gift at times, they can also feel like a curse, especially when the intensity of them leads us to feel like we're falling apart. In my opinion, 2 of the toughest emotions to manage would have to be heartbreak and complete and utter despair. They're so incredibly painful. It's amazing how heartbreak can feel so physical, that aching in the chest. Mending a broken heart can require not just simply time but a management plan. How we manage healing is what can make the difference.
Have you considered ways to manage? While self harm is one way, of course, as you would already know, it's not the best way. Have you considered opening up to your partner or perhaps looking into some grief counseling? Do you have someone in your life who is sensitive to emotion, who can relate to the mental and physical impact of it? Someone who has an understanding of emotion coupled with a balance of managing their emotions could be the person to speak to. It sounds like you may need someone who deeply feels for you in the incredible challenge you face. I believe, such a person would make a good listener, giving you the opportunity to really vent. It's so important to release heartbreak.
Di, at 50 I'm still coming across emotions I've never dealt with before in my life. I'll continue to come across those which will really test me, such as losing a family member. I'm very sensitive to emotion and know I'll need to manage carefully. Managing is how I've so far mastered not returning to depression. While my 15 or so years in depression is behind me, there are times that can have me fearfully standing on the brink, looking into that dark abyss. While intense emotions can scare and drain me, I know they're also challenging me in some way, to reform myself. If only there was an instruction manual for life with a chapter on 'Managing extreme emotion'. I'm sure emotional exhaustion would be included.
On a lighter note Di, do you enjoy your job, even though it's stressful?
Take care :)