I'm really sorry to hear all this. It is really strange, isn't it? My dad wasn't very involved in my life growing up (saw him a few times a year, never spent the night at his house or went out to do anything together, he'd come to my mum's for lunch for a few hours and then go home and I'd not seem him again for a few months). He died when I was 18. I am NC with my mum as she met and married a child sexual offender about 15 years ago.
In an odd way, I find it all quite normal. I've never had a loving two parent family growing up and I've spent more of my adult life than not without one/both of my parents. So it's my normal now. But there are days when it still knocks the wind out of me.
Like Christmas, I find I really struggle with dh's whole family being all over us, staying with us, showing up with gifts, coming for meals, just lingering about. They are absolutely lovely. But I find it's really too much to have them here a lot of the time, and I think it's because I can't grasp what it's really like to have family who love you and want to be in your life. Just seems very foreign.
I also look at my children and am just astonished at what a strangely different life they have to what I know. They have two very involved parents, who live together, love each other, are dedicated to them, come to school activities, etc. Some days I think I'm doing a crap job at parenting and life, but I try to remind myself that so far, I'm holding it all together better than my parents did, so that has to be something.