Hi, I’m in your exact situation but a couple of years older.
My ex also lives in our old marital home with his girlfriend (who was a mutual acquaintance before also going through a divorce and she and I became very close (so I thought) and exchanged confidences and condolences) My child and their partner also play happy families together. I also ended up accepting less money than fair in the divorce simply to get away from him.
I am currently renting while looking for a permanent home, closer to my child.
I find reframing things helps. I left my ex because he was a manipulator and a lier. He was always looking for the next thing to make him happy - but was never satisfied with his life even when he seemed to have everything.
He will never change and I console myself with the thought that he will inevitably find fault and be dissatisfied with his new relationship and situation. He is also still grossly angry that after a 30yr marriage the Law should even dare to think that I deserve 50% of our assets. I’ve ended up with less but it’s enough for me.
He looks as if he has everything, but I know him so well - I know that having everything still won’t be enough for him.
Even after 3 years, I still awake each morning (on my own) and bless the fact that I am free of him.
I have taken this opportunity to assess myself and discover what this new me wants from life and what will make me happy. Knowing this, I am forging a new life and lifestyle to take these things on board.
I have had therapy and been reading widely. I now know all about Radical Acceptance, Ikegai, ACT Theory, Let Them, and so many more. I pick and choose anything I think will help me from each of them. I have reached out to other organisations for help and support; The Freedom Programme, Fear Free, Mind etc.
Counting my blessings and relishing my new found freedom everyday helps me so much.
I am still trying to work out the proportion of social activity/engagement, meaning and purpose and peace and calm I need to be content. I have found the phrase Stay busy, be Useful very apt.
So in summary, regarding your ex - things aren’t always as rosy as they seem.
re being single - by knowing yourself, you can build the life you need and want to make you content/happy.
For the first time in a long time - your life is now your own to control - that is a blessing indeed.