Fuck cancer. Fuck cancer. Fuck cancer. Fuck cancer.
Now that I've gotten a little bit of my anger out for the situation you're in, I'll try and offer some advice.
Not all cancers are the same and not all cancer stories end the same way. It may turn out that the biopsy reveals that it's a more treatable/curable one in an earlier stage. Regardless - I think it might be worth seeking support in the form of a psychologist or such. You've said it yourself - you're going through an extremely hard point in your life and there is no shame in seeking support off the bat before anything progresses.
My mother is currently stage 4 and receiving treatment - she's a big part of my life also so I feel I can understand at the very least a bit of what you're going through. I think (like I've been), you're looking for some reassurance on how to survive if things go south. These are the things that I've learned on the way of my own journey through all this bullshittery - with any luck, you might find some value in this.
Reach out to people and establish a support network for yourself. I've had cases where I've cried on the phone to other family members as well as friends and they've just listened in for a good 10 or so minutes. It's not much but even the little things they do help and make you feel less alone. It helps remind you of all the people that care and love you too. Certainly my mother knows that I'm rather distressed (which is putting it lightly!) about the situation she's in and we do talk about it but at the end of the day - I'd rather try and focus time with her doing happy-ish things (even if it's something like watching a new episode of a netflix series)
Do try and establish a sense of normality for yourself (keep up a hobby) but also try and establish a sense of normality when you're with your mother too. Don't try and be happy happy all the time but a great way of supporting my mother has been doing stuff like netflix and just enjoying each other's company. Even if it is cancer - it does not kill overnight - you still have time with your mother. Find ways to enjoy it! Take photos, videos and have a good time as much as you can while maintaining/balancing that with your own life.
If she does get bad results back as my mother did, another thing to do is research and staying alert. Doctors want patients helped and cured but sometimes don't take into account how medications can affect different people or alternatively natural medicines can which act as a complementary treatment (AKA - how do the medicines affect quality of life?) . One of the reasons I'm on these forums is because I originally came here looking for information and knowledge as a way of 'doing something' I now stay mostly because one of the things my parents have imparted in me is a sense of 'help others' so I try and honor that by being here.
Hope this helps a little bit and wishing you and your mother all the best. Keep us posted - there are others on these forums too but everyone visits at different times 🙂
