Adoption

So this past week has been very interesting for me. I received a letter from my biological father. I also was shown a letter dated back in 1990, telling my mother that she put me up for adoption.( From my biological father). So I really don't know what to think. I am really happy that my mother didn't and I am very upset at the man in question. He told me in his 4 page letter that he would like to meet me/ but only if I wanted to. And I really don't know how to feel. This is a man who for 18 said or sent nothing to me.