I found my dad... now what?

I just need to get this off my chest and, in the process, maybe get some advice.

Basically, I have never known my dads side of the family. My mom and him got divorced when I was very young and my sister was still an infant. She always told me awful things about him and his relatives, and until I was 15 or 16, I believed her. But since cutting my mom out of my life, I've been wanting to get in touch with them, and I finally did. I found out I have several aunts and uncles, a plethora of cousins, and... a brother. My mind is blown right now, because I never thought I'd have this much family.

But now I don't know how to connect with them. They're total strangers. I feel awkward messaging them. But I know if I want that connection, I have to try. What do I say? What kind of questions do I ask? It's so confusing :(

Has anyone else been through something similar, and if so, how did you go about it?