It is exhausting carrying it all around. It's really great you recognise it though as those are all the first steps. You will get there. You're working through it all.
I think when we carry all this shame we assume others are going to judge us from that same shame lens. But how we hold it is going to be very different for them. It may be a complete 'non issue' for them.
It took me 16 years to tell my partner about my trauma. Wasn't 'lying' about not sharing before. Just unable.
The fact you had a different name and you changed it comes from trauma. So maybe it's not so much 'i have a secret I never told you about my name's but 'i now feel able to talk about some of my trauma with you and that made me change my name'.
Maybe shifting how you see this telling/sharing?
Edit to add: if my partner told me that they had a different surname before and never told me. I really really really wouldn't think it was a big deal. I'd ask why. It would be the why that was the thing. If they changed it because they committed crimes and wanted a different identity -that would be an issue! But any other reason would be fine. I wouldn't feel lied to or that I couldn't trust them.
Yeah, family are their own shit show. And that's a whole other thing to navigate....