How long can grief-related spiraling last after losing a parent?

After my mom passed away my older sister has been spiraling. She has not gotten sleep and she has been saying some hurtful things and scaring her husband, her daughter and myself her younger sister. She is now in therapy and will be there for 5 days but I would like to know if anyone has gone through this? Has anyone in your family spiraled and how long did it last? Or nothing changed or got worse.. anything will help. This is the first time we lose someone in our family and we lost our queen
How long can grief-related spiraling last after losing a parent?
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