How can I get my dad to accept my biuality?

So I went away to a facility 8 months ago and just came back in April. While I was there I became attracted to this girl and realized I was . I told my mom my dad my stepmom and one of my aunts and my mom stepmom anda aunt was accepting of it but my dad thinks that it is just a phase and doesnt really understand it. Last night I asked if I could to a pride festival with a friend at the end of june and he said why would you want to go to something like that. I was like do you not realize that I am a biual and he got real quiet for a second and said I still think you will change your mind. I said well mom accepts it so I hope someday you can too. I havent told the rest of my family and Im afraid they wont accept it especially one of my uncles who is a real redneck. Im afraid he will hate me or something. Im hanging out with this girl that I have been talking to for a few days this weekend and she is going to meet my family. What should I do? Should I just come out and be like hey I have been talking to this girl for a few days and we might start dating? I dont know what to do!!