How can someone who was groomed as a child unlearn the lies and grow in their thirties?

I suggest therapy instead of asking random people on social media. This sounds way too important to leave to Lemmy comments.
- While yes, there are barriers to access for a lot of people there. Support groups - exchanging insight with people who have been in similar situations - tend to be pretty effective, and Lemmy is just acting as an online front for that.
  I'd take anonymous internet comments with a grain of salt, but with that healthy skepticism in mind there's plenty of potential for healing even in this environment.

I probably have no business commenting here, but I'm gonna post my thoughts anyways.
Forget the idea of intimacy, however long you feel you need to. Find an innocent hobby or skill, study it, master it as best as you can, and be proud of it.
Be proud of yourself in general. If you were abused, you shouldn't be ashamed, your abuser should be ashamed.
If you do eventually find someone worth love, be open with them. They should understand and respect you and your boundaries.
Take life at your own pace, don't let anyone else abuse you again, and take my advice with a grain of salt.
Disclaimer: I'm no expert, but I've had friends that were abused ☹️

53 years old here. Still peeling that onion.
But it tastes better, every layer. I guarantee.

I don't know what your experience was like, I want to make it clear that how I handled my stuff def wouldn't work for everyone.
For me, I found that it was hard to find a healthy relationship because I was attracted to and attracted abusers. It took me going open poly and having a lot of casual, relaxed, and actually intimate encounters with people to over-ride my insecurity and lack of self-worth. I was in an open poly relationship with two wonderful people for about 4 years, and had casual fleeting relationships with people throughout.
I learned how to set boundaries. I learned the language I needed to express those boundaries. I learned how to communicate my needs, and how to process experiences in a healthy way. I learned that there are no perfect people; that everyone has damage.
I also started doing "the work" by Dr. Robert Gibson. Its a series of 48 tapes that guide you through a process of introspection, so that you can face the hard stuff and move forward. It can be scary to look inward, and a lot of people avoid doing so and throw themselves into distractions. I did that for years, and I still struggle with it sometimes. If you look for the tapes, I warn you that they are framed in a pseudo-spiritual fashion, if that happens to be triggering.
At some point, I got to a place where I could identify what I wanted in a relationship. What I needed, even. I went out and found it, and am now engaged another four years later.
I genuinely hope you find a way through that works for you. Big hugs <3

Connect with peers.
Plenty of people grew up in similar circumstances. There are all sorts of self help groups. A good therapist would be able to help you find them.

Cognitive Behavioural Therapy
Will change your life.
Get help if you can. Buy a book with worksheets. Whatever. Dive in.

What kinds of things are we talking about here?

Make friends with and live with people who aren't living the indoctrination setting you were brought up in.
Even then, I'll probably be deprogramming from some stupid shit I was taught all the way till death.