Thank you so much for your honesty in your post, and a warm welcome to our forums.
I am so so sorry to hear about your dad's passing. Truly. Losing somebody in the family is never easy, especially when it's a parent. While I haven't experienced the pain of losing my father, I have experienced the pain of losing my grandfather in a similar way to what you have described for your dad. My grandfather also hated hospitals, like your dad. It's so difficult seeing someone you love in a hospital setting in any capacity, especially when you know that they don't inherently want to be there.
After my grandfather's passing, I also felt like I was drowning and that I was a burden to everyone. That's a very normal reaction. Just know that it's okay to grieve, and that everybody deals with grief in their own way. The grief journey is never linear, and you may find that your emotions will fluctuate from time to time. If you feel like you need to cry or let out your emotions, feel free to do so. If you feel that you need some time and space to process your feelings and be alone, give this to yourself. If there's anything I learnt after my grandfather passed, it's that it's so important to nurture yourself and give your mind and body what they need.
If you feel comfortable and have a good relationship with her, you can always have a talk with your mum about your feelings. She can likely relate to a lot of what you're feeling at the moment. If there's anyone else in your immediate or even extended family who you would be able to talk to openly about how you're feeling, I find that this is a great way of expressing your emotions with each other, and even bonding over shared experiences that you had with your loved one during their lifetime. Reminiscing offered me and my family great healing, and also allowed us to share our feelings with each other and grieve together.
Have you tried or considered talking to your GP, seeing a therapist, counsellor, or psychologist? You can always have a chat to a mental health professional about your feelings, and they may be able to offer you some professional advice to help support you on your grief journey.
I wish you and your family all the best during this time. Please continue to chat with us on the forums, we're here to support you during this time.
Sending all my love, SB