I can definitely empathize with you. My mom is a bit of a narcissist and when my dad died she was at times pretty disrespectful about the fact that I was grieving too. When I confessed to her how stressed and overwhelmed I felt dealing with the aftermath of losing a parent so young (I was 26) , she basically told me lots of people have it worse, that I was playing the victim, and to get over it. Meanwhile at this time she depended on me to help her do countless things, for example go with her to traffic court after she ran a stop sign, because she would break down crying all the time. It really sucks to feel like the relationship with your remaining parent isn't mutually supportive when you're dealing with loss.

That being said, I sucked a lot of it up because the fact is losing a spouse is usually harder than losing a parent. Your dad lost his life partner, the person he has spent the vast majority of his life with, built a family with, even if she was not perfect he is feeling intensely alone right now. Try to imagine being in that position.

Don't feel guilty for how you feel about all this, you can't help it, all you can do is try to process those feelings and let them go. Recognize that your dad is going through intense grief and also cannot help how he is grieving. It's ok to be assertive sometimes and remind your dad that you are grieving too, but when it comes to things like his rewriting history and the constant crying, that is just how he is processing it and you should allow him that, there is no wrong way to grieve. Get yourself a therapist to hash out all your frustrations with. Things will suck for a while but I promise it gets better.