I was once taught a technique for another problem I had. It worked well for me and could be applicable, so I'll share:

I was told to imagine a large heavy box that can be locked. It's helpful to imagine it in detail and make it your own. When a situation comes that would make me have the problem - in your case, something happens that makes you feel like oversharing - put it in the box and lock it.

It's there in the box and you don't have to deal with it right now, it's going to wait for when you have time to deal with it in a healthy way.

Now the important part: find a time in the day when you feel comfortable, just a few peaceful minutes for yourself that you can have regularly every day. Make a coffee, sit down - anything that makes you feel alright.

Every day, in the designated you-time, open the box and take a look inside. Go back to what you've locked in there and evaluate. Now you have time to deal with it. Is it something that needs solving? Is it something that makes you feel certain way? Is it as big of a deal as it was when you locked it in?

Now you have time to really deal with the thing that made you upset. You will be better equipped to deal with it in the designated time when you feel alright and can focus on it. Often (though not always) you'll find the thing shrank or disappeared completely during it's stay in the box.