Hey Melaniejm,
So sorry about your mum and what your going through! it must be hard, where are you in relation to getting support professional or otherwise? you definitely deserve kudo's for having the courage to join! as well as being a single mum and no doubt being there for your father too already speaks volumes of your strength and courage.
we are only human though and get weak from time to time. just don't feel guilty for how you feel, with everything your going through your entitled to those feelings and should embrace them when you can to fully release the emotion you feel, I think everyone feels better after a good cry!
I lost a couple of parental figures over the years. one of which his funeral was on my birthday 4 years ago which always brings up memories of him obviously! he was like a father figure when working from a young age and the other was an aunt who was like a mother to me when I saw her, I lost her to breast cancer and couldn't attend the funeral as it was abroad. I also lost a little stepbrother when I was around 7 which was pretty traumatic too!
the thing I find helps even just a little is being gratefull that I had experienced that person in my life. that we were able to share memories and learn from eachother. I didn't have much to relate that to my brother as he was still born but I cherish the 10 minutes I spent with him in the chapel of rest.
other advice is to read through the topics in the relevant sections and relate to other peoples experiences and advice.
you may see what your going though as being unfair on the people around you as your meant to appear strong which is completely understandable in your situation! you are only human though and given time hopefully people will understand... lean on friends if you can for support, failing that there are people here who are so helpful and kind, theres always a warm welcome here!
hope your doing okay and staying strong!