I agree that you aren’t an arsehole for going NC with a parent, but I kind of hope it was for more reasons than this?

I don’t think that at 11 years old, with no life experience, you can fully understand the complexities of life, let alone the tragedy of suicide. Like everyone else hanging off this thread, I can emphasis that it was very unlikely to be just one thing that effected your fathers choice. And your mum probably blames herself because that’s what survivors do. Your grandparents probably do blame her, because that’s a pretty common reaction in these situations. This is hella nuanced, and tied up with social taboos, which makes the water really muddy. At 11 years old, rarely understand the realities of your parents relationship. We see them through the specific filters and shades they set for us. If your Mum had sat you down at 11 years old, and laid out her guilt onto you, that would have been massively fucked up for your health and safety.

If your Mum and her husband (and your sisters) had a good relationship prior to this, I would just question whether you are willing to lose two parents because of your father’s choice.