Dealing with a new relationship

Quick backstory, together 14 years married seven, it’s not been good for a while and she tells me she’s checked out.

About a month ago I had a hunch that something was going on as she was been very cagey and had her phone with her all the time.
Then one Tuesday about two maybe three weeks later whilst I was at work, (I’m a lorry driver, so stay out most of the week)
I got a message from her explaining that she met someone on Hinge And they were just taking it Slow, et cetera

When I got home, we sat down and spoke about it and there are times where she’s okay about it and then there’s other times where she seems to be rubbing it in.
(we’re both white, I’m 6’1”, reasonably slim no tattoos etc)
(Not that I have anything wrong with black people) but he’s black and she seems to be explaining in detail certain things I don’t really need to be knowing (BBC) and how she’s always loved black men or men with tattoos, gym bodies etc the bad boy type.
When I asked her why she settled for me when we first met then as I’m the complete opposite to any of that, She couldn’t get me an answer.
Last week she told me that they were moving a bit too quick and then they were gonna take it easy and see how it goes.
Then she text me just now saying that she’s going out Friday night and will be back about midday Saturday, I asked her if she’s going out with him and she said yes

I really don’t know how to react to this, it’s really getting to me the fact that I’ll be sat at home with our three children whilst she goes out and gets railed by someone else.

How are people dealing with their ex moving on and meeting someone so soon, especially as I still have quite deep feelings for her?