Endless crying - warning content about grief/cancer

I lost my dear dad 6 weeks ago this coming Thursday and I feel as if I will never stop crying? My period just arrived after being 5 days late from stress no doubt and it feels like a ton of bricks. Anyone have any advice for dealing with this type of grief? My dad was sick with lung cancer for 3 years before it spread to his brain just before Christmas we finally lost him on April 15th. How do people manage this? I feel utterly lost.

Thank you so much