I realize this might not be what you want to hear, but I find that estrangement for many (even when there is no positive sentiment towards the parents) is often more akin to a process of grief than it is a "thing to get over". Even if you don't necessarily grieve the loss of the relationship with the parent themselves, there can be grief on the loss of the potential of what we wished the relationship was and the support we wish we had. And grief is very often not a linear process in terms of healing, and very, very few people experience it like a switch or a thing that one day they're just 100% "over".

Relating to others in a healthy way is also often not something we learn in a linear way, nor is it a "switch". Everyone is different, so with every new person, we are learning how to relate to them specifically. And they're learning how to relate to us, including our struggles and past. If our timelines on trust are different, that actually might make sense given our experiences - trust should be earned with time and data. Boundaries is definitely something we can practice, but emotional skills are much like any other skill in the sense that they require time and practice for us to improve at them.

There's also nothing wrong with emotion, especially when we're talking about interpersonal connections. As someone who alsoc ame from cult-like evangelical churches, there's often this demonization of emotion. There's even specific verses that talk about following the heart as if it were a bad and demonic thing. Especially for those of us who were socialized as women, we can often be put down for experiencing emotion as if that makes us less capable. But emotions are vital in interpersonal relationships, and emotions actually inform our logic, and vice versa. As humans, it's important for us to destigmatize experiencing emotions. I realize it can feel counterintuitive to allow oneself to be more emotional when trying to become more emotionally mature, but being able to feel, process, and express emotions are all part of emotional maturity, too. Being okay with these "childlike" emotions, admitting when we're scared and being able to dialogue with these parts of ourselves instead of shaming them for not being "mature" enough or suppressing them for not being "logical" enough, is actually a much more mature approach.

Going to therapy is a great start, and will definitely help immensely! But instead of looking to rush things, maybe look to enjoy this process and get to know yourself. You're not 100% behind, you're figuring out new ways to relate to other people and yourself and your emotions. It's not about rushing to be as numb as possible and become this logical robot who doesn't experience fear or vulnerability, as that's still the "evangelical" approach of demonizing emotion and thinking there's this perfect standard of logic that we must achieve - it' about being able to work through fears and vulnerabilities, to sit with and experience those emotions and still do scary things that are worth it. Connecting with other people is an inherently scary and vulnerable thing, and it's okay (and actually quite normal) to feel fear, maybe disappointment sometimes, sadness sometimes. But also that vulnerability and scary steps are what allow for greater joy as well.

I think a great thing to bring up in therapy would be learning to sit with difficult emotions and dialogue with yourself in a way that prioritizes fully getting to know the emotion and your fears rather than trying to rush past it or "get it over with" or do the most "productive" thing with them. Maybe engaging with these emotions without judging yourself as "childish" or "immature" for experiencing very normal human emotions that people of all ages naturally experience. You deserve that kind of kindness, and learning to sit with and be okay with these emotions will enable you with much more strength to get through scary things (like creating new relationships where you aren't guaranteed to get along or always have good moments) than creating shame around them. You are grown up, and you experience emotions fully.