The feelings you describe make the most sense to me - to feel the most anguish when loved one dies by their own hand...a choice they made... no matter what the reason.

It's very different when death is by illness, accident or even murder - you can hate the murderer and be angry at the illness or blame accident. Totally normal and acceptable.
But this way, being left with only the loved one to be angry at , but still deeply mourning for the loss of has got to be the worst feeling ever.

If I ever had to go through something like that-
I hope, eventually, that I would be able to look at it from the point of view that the person must have been in some horrible physical or emotional pain and not able to see anything but a bleak future of the same.
They make the ultimate decision from that bad place that ends their pains, but leaves the loved ones with so much more pain and most likely feelings of guilt.

The anger, love, longing and guilt are a major mix of emotions to move through .
I hope the best for you soon.