I think my colleague might be my half brother how do I tell him without sounding crazy?

My dad and mum were never married and we're in a very toxic relationship because of us this I never got to meet him or know anything about him. my mum kicked him out a month before giving birth to me for being physically abusive towards her.

His name was never on my birth certificate so I never had anyway of finding him and I was only giving small details about him from my family.

23 years go by and I meet a guy on my training day at work. I embarrassing if what I think is ture but at first glance I thought he was really cute. me and some of the girls on the training day were talking boys in the girls toilets and I said but I thought he was cute. One of them said "If I'm totally honest I thought he was your brother or something" and all the other girls started saying how alike we actually looked.

After that I found it super off putting and no longer thought he was cute. We still became really good friends and we were already have a very stister/ brother relationship already. We got talking on a night out and turns out neither of us have a dad. He told me his dad was abusive and he died in a drink driving accident when he was 12.

He told me his dad worked in a factory which also happened to be the factory my dad apparently worked at too.

My grandma would tell me little details about my dad but my mum would soon try and shut her up as she didn't want me having anything to do with him so I knew some stuff.

My grandma always referred to my dad as "that ginger prick" in the picture of his dad that he showed me he was a red head.

I didn't say anything to my work friend but I just remember feeling sick to my stomach and panicked. I soon left and went back home as I felt really conflicted. I couldn't sleep all night so I went to my mums room and confronted her about her not telling me enough about my dad.

Updates
1 y
It a very big factory that employs a lot of people so it's not for definite but we do look exactly similar and the picture of his dad he showed me looked like us too. i don't know if he showed me this because he was thinking the same too but I might be his stister
I think my colleague might be my half brother how do I tell him without sounding crazy?
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