Seeking support as I connect with a biological brother who was adopted out at birth: my father had an affair.

Hello everyone, I have a complex situation on my hands and don't really know how to deal with it. When I was about 6 week sold (I am now 39 years) my 23 year old father had an affair with a 16 year old girl and conceived a son who was adopted at birth. That child, who is my biological half brother, just made first contact with me about 3 months ago. We determined a positive genetic connection through DNA testing, and that he looks exactly like my dad is kind of mind-blowing. At first I was eager to connect with him, get to know him and share positive stories of my father, who is now dead. My bio half brother has connected with his bio mom and her family and has had a positive experience with them. The problem with my side of the family is this: My father was an abusive alcoholic who abandoned and neglected me when he remarried my step mom. He never wanted me in the first place… he had multiple affairs when he was married to my mom, and the pain of that abandonment is still very real for me. So enter stage left, bio brother who was conceived in an affair when I was 6 weeks old. Now, my bio half brother wants to learn more about his adoptive dad (my dad) because of the very real abandonment he naturally feels by being adopted. I totally understand that. I want to welcome him into my life as much as possible, and hold space for his feelings of abandonment. But in doing so I am forced to relive all the abuse, lies, neglect, abandonment, violence and the daily reminder that I was not wanted either. I have just gotten to a point in my life where, thanks to lots of therapy and meditation, I have begun to heal and move on and really let go of the trauma of the very real abuse. And I don't know if I want to reopen the door right away to more reminders that my father didn't want me and that he didn't want my mom, and the very existence of this bio half brother confirms that: he was conceived in an affair. The other issue I am having is when bio brother refers to him as "our" dad. That is hard for me, because bio brother was adopted into a stable, loving family who actually WANTED to have children. He actually had a dad. Whereas I didn't have a dad… my dad was to consumed by his addictions and was wholly neglectful of me. I feel envy that bio half broth had a dad. He grew up in a stable loving family. I didn't. Now, bio half brother wants to get in touch with my dad's brother to learn more about him, which I think is natural. But, it puts me in apposition where I am not ready to open up this can of worms because it has the potential to reveal more lies that my father and his wife and my other half siblings kept from me. They were all vey active in withholding information from me and lied to me most of my life. If bio half brother connects with my dads brother, who I am not even in contact with, I feel unprepared for what else I might find out. I want to connect with Bio half brother and share with him the truth, and hopefully grow a relationship with him. But I want to set boundaries that feel safe for me, while also respecting his right to know who he comes from (actually, I am confused about this because it was a closed adoption that was opened for medical records purposes). Does he have a right to know everything especially if the cost of it causes more pain for others? I want to support him, and take care of my own grief. I am open to support and feedback…. How can I set healthy boundaries that protect me, but also honor him and his process of discovering who he is? Thank you, Nicholedanielle