Oh OP. I had an abusive and neglectful childhood include sexual abuse. I am no contact with my parents. I was lucky to have a supportive step parent who is still in my life (and no longer in a relationship with my parent).
I went off the rails and struggled with alcohol abuse in my teens and early twenties. I was lucky to hit a very painful rock bottom and loose a relationship I was happy in as a result which snapped me out of it. I got sober, had years and years of therapy (still ongoing) and am now in a good place and at peace.
What happened to you and to me was wrong and unfair. Every child deserves to be loved and cared for unconditionally by at least one person. When that doesn’t happen it is soul destroying. It is so important to remember that that says everything about them and nothing about you. You are not unlovable and you have value.
Some things that might help:
Try and reframe your current situation. You have no ties - instead of seeing that as sad can you see the opportunity? If you are unhappy with your job, no caring commitments and no mortgage you could do anything. You could move countries, you could go and work abroad - I know people who have done work for board and basic pay on farms in Australia and had a great time. If you enjoy meditation could you look at a meditation retreat abroad? You may need to save up but that would make you feel like you were working towards something.
Would like to foster and give a child what you didn’t have? If so looking at what the requirements are for fostering or getting in touch with your local fostering team to ask questions could be wonderful and very fulfilling. There is a huge shortage of foster carers and they are very in demand.
Alternatively you could look at volunteering for home start, they are volunteers who go and support children and families - visiting to help parents who are struggling by playing with the children maybe, doing a bit of light housework, being a listening ear. A great opportunity to help children and parents to feel supported which could make a real difference to their lives.
You could also ask if your local primary school need a volunteer to come and listen to children read though this would be school hours. You could volunteer in a hospital - this may be taking the tea trolley around etc. not necessarily with children but you would be benefitting others and it can make you realise how lucky you are to be well enough that you are not in hospital. You could speak to a local care home about becoming a befriender or visiting someone who has no visitors/family. They would be grateful for the companionship and if you build a bond it could be a nice way to get advice and wisdom as you would from an older relative/mum/grandparent.
Slightly different again but you could volunteer for a dog rescue - playing with the dogs and taking them for walks, things to love which will love you unconditionally back. There is a riding school near us which is a charity and offers lessons for disabled children - horses can be very soothing so something like that could be great. Or volunteering abroad - I did this and met so many people living in awful circumstances who were so happy and content despite it. This really put my life and privileges into perspective.
If you feel angry you could try a rage room or take up boxing. If you feel powerless a self defence class or something kind of assertiveness training might be good. Toastmasters is a public speaking class/group which is supposed to great for building confidence generally and meeting people.
Imagine that you were 80 years old and then woke up tomorrow and found you were 42 again. You would be so delighted and happy to have all those years back and so many things you would want to do. I am working on a list of 100 dreams at the moment - things that I would like to do in my life. When you start it will probably be big things - go to Australia, go skydiving etc. as you keep going list everything you can think of no matter how small. Making homemade pasta is on my list because I’ve never done it and would like to. Collect as much inspiration as you can - a list of restaurants you’d like to try, day trips you’d like to visit, musicians you’d like to see live.
Any of those things could be the start of a community / new friends and connections. I have found church excellent for community, very friendly and welcoming. You may discover a deep faith or just enjoy the companionship and music etc. they tend to have lots of things to get involved with, socials, and you could potentially volunteer with them at Christmas for example or go to a service on Christmas Day if that is normally a difficult time.
Look into some inner child work - parenting the scared little child inside you. Again this can be very healing.
What happened to you was not fair and out of your control but now you call the shots and you get to decide who you spend time with. If your job is making you unhappy look for a new one and start fresh. You only have to share as much about your background as you want to if you are worried about people seeing you as weak.
Lots of the ideas above probably won’t speak but if one or two do then take some action and go and try something. We all need purpose and meaning to feel fulfilled. Be very kind to yourself. Taking action will always feel better than ruminating, don’t allow the people from your past to rule your future. I wish you the very best of luck.