How do uou stop worrying when your children grow up?

[midlifebreakdown]

DD1 is 21 and is neurodivergent. As a result of this I have been more involved in her care for later than average young person.
In the past month she has changed from being a complete home bird and never wanting to go out without me to being seeming resentful of my existence and being out most days and nights until the last possible moment or not coming home at all.
I am delighted that she has friends and is starting to become independent but I am not handling it at all. I am not sleeping until she gets home so I am exhausted constantly or worrying when she is out and it needs to stop.
How do I shake myself out of this?

I'd also be looking into who these new friends are. Especially as it's such a recent change and she's vulnerable. If it's all above board and she's spreading her wings, then ok. But still keep an eye. But this situation would have me very concerned.

It is other young people she works with. I know a bit about one of them and I know that they have waited with her to make sure she is on the bus or a taxi but there are also some things with that person that worry me. Mostly around minor drugs and some things they have said or done that have been a bit toxic.
She went on a day out with another one of them and the parents went and were really nice.
The others I have no idea.

She works part time there and has for the last few years as have most of them.
Apart from a whole work Christmas meal she has never been out with any of them until this last month and has never shown an interest in doing, In fact she has had several fallouts with one of them at work due to some of his behaviour and has actually complained to her manager about some of his actions.

It is worrying me greatly but she is legally an adult and has already pushed back enormously at my reaction to her being out so much and so late so I am unsure what I am meant to do.

She is 21, and an adult. I would leave her to it and be grateful she is going out. She will learn through her own mistakes. It's a transition for you so distract yourself from worrying.

You can surely discuss your concerns and trust them to make their own decisions based on their own values. This is how self esteem develops and good relationships with parents are maintained.

I do understand that, I really do and I have been trying.
I have had conversations with her about staying safe and getting home safely.

The problem is that while she is an adult. this is an adult who is vulnerable and has issues with recognising danger and keeping herself safe and I am going out of my mind. T

She has also pushed against any discussion with her or any worry I have had on a huge scale.
She feels like I am treating her like a baby and am unreasonable which I know partly I am!