1. Parenting in reaction to the way your parents interacted with you means their failure still controls you.
It's tempting to look at the things your parents did that hurt you and vow to do the opposite. But when you do that, it means your parents are dictating the way you parent your own kids. So they (and the things they did or didn't do that hurt you) are still controlling you.
One of the running themes I've noticed is parents who didn't seem to see who their kids were or what they really needed. Parenting the opposite from the way your parents did puts you in prime position to do this to your own kids, because you're not focusing on your kids as individuals–you're reparenting yourself instead. My mom laughed about this when I was maybe 6 or 7 and we were at the shoe store. She wanted me to get black patent Mary Janes, but I wanted the brown lace-ups. Finally I broke down and wailed, "Mo-om, I don't want the fancy shoes!" My mom stopped, thought, and realized that when she was that age, she'd always wanted the fancy shoes, but her mother had always made her get the sensible shoes (she already had 2 or 3 younger siblings by that point, so the shoes had to last). So she was forcing me to get the fancy shoes because those were the shoes she'd always wished she'd gotten but could never have.
That's obviously a trivial example, but it does show how you can do this stuff without even thinking about it. But once you do think about it, and expose it, you're not held hostage by it anymore.
Instead, by identifying and releasing what happened to you, you're saying "This wasn't healthy." Then you can calmly figure out what is healthy and start there with your own kids.
2. Giving your children what you didn't get from your parents won't make up for what you didn't get and it won't make it OK. But it's better than repeating the cycle, and it gives you a good relationship with your kids.
If your parents aren't capable of it, you will never get what you need/ed from them. There isn't anything you can do about that. Let yourself grieve/rage/sob.
Even being the best parent you can possibly be won't bring back what you lost from your parents. But at least you know you're not doing to your kids what was done to you. And you're also creating the connection, space, and boundaries necessary for a healthy relationship and closeness with them for the rest of their lives (even though they'll eventually leave you physically).
3. There is no such thing as perfection. But you can do better than your parents did. And you'll hope your kids do better than you did.
My mom is not a perfect mother. From her point of view, she yelled too much. (She pretty much did. Although sometimes we deserved it.) She had other imperfections, too. But she parented me better than her own mother parented her, and my grandmother parented my mom exponentially (truly miraculously) better than her own parents parented her.
That's what's supposed to happen. It is absolutely not possible for you to parent your children perfectly. No matter what you do, they're going to be screwed up somehow. But if you can do better than your own parents did, you're honoring your children. (Those of us with parents who are pretty healthy have probably already heard them say some version of "I know you'll do a better job with your kids than I did with you" and mean it.)
So good news for those of you who got a truly raw deal–you have plenty of room to make some huge mistakes and still have your kids come out of it saying "I have no idea how my mom was such a great mom, especially considering how she was raised."
4. You have the ability to get a reality check.
Something our parents, isolated in their houses and apartments, never had. The internet is here so we can talk to each other and say things like "I freaked out on my toddler in the middle of the night and am afraid I've ruined everything" and there will be people there to tell you to apologize to her and start again in the morning. Or, conversely, to let you know that it's not a realistic expectation that your 4-month-old be able to entertain himself for an hour at a time.
A friend of mine grew up with a mother who never quite recovered from her divorce and was quite bitter about it. My friend said she wanted a healthy marriage and family, so when she was in high school she started spending time at the homes of friends with together parents and happy home lives. And she paid attention to everything and filed it away. She knew she was going to need to see it modeled if she wanted to replicate it. Super-smart cookie, my friend. She knew the danger of being stuck in a feedback loop with only yourself, so she started building a file of reality checks for herself long before she needed them.
Ok, what am I forgetting?