It is a horrible thing to watch someone die. Even and especially by slow degrees; chronic illness, terminal disease-one and the same?-mechanical pantomimes. It is a slow torture for all the parties involved, and anyone who would say different is either daft or selling something.
She's gone now, and, as the worst kind of bastard with the morals-ha!-of an alley cat, as your friend, I can only speak in truths...
You are not going to get over this. Ever. Sure, after a while you reach a point where the void where that person was is not so cold and bottomless, but it'll always be there. Something, anything, will reach out of the nowhere and remind you of what you've lost. What was once there and can never be recovered.
There will be regrets. All the memories and stories and little moments. Gone now. You will wish you listened more. Took more note. Relished those small times. Shown more gratitude for what was soft and warm and unspoken.
You might not sleep much at first. Your dreams will be haunted by that phantasm. Then, one day, you will just crash; entering into a dreamless sleep that seems to last for days. That may just be the day the psychic scab starts to form.
Cry. Be angry. Shout and scream and punch something. Purge the ire, do not let it fester and poison you. Mourn. Allow yourself that.
Watch the sun rise. Watch it set. Snuggle with your daughter and your boyfriend, perhaps at the same time. Tell stories and smile. Walk. Breathe. Live. Allow yourself that.
It's not going to be easy. How the fuck could it be? This is Hell and cobwebs and gravedust and razorblades and maggots. It'd be an outright lie to say otherwise.
But, you're a fighter. You will survive this. If for no other reason than it is not in your nature to just up and quit.
It's a horrible thing to watch someone die. I know this. You know this. We've both been here before and we'll be here again. That's just the way of it. Just know, I can only speak to you in truths and I've got your shadow.