It is difficult to determine who is more naive: YOU or your FWB.
YOU chose to have unprotected sex with a man whom you don't believe would be a good father, and, by extension, a man whom you consider a poor choice as a life partner ("not father material"). His only value to you is as a sex partner, one who stimulates your glands but not your brain or your soul. NOW you're thinking you may be pregnant. Who would YOU blame for this decision?
HE tells you that being 33 years old is "way past the age of having children." Either he has a very poor education and believes that his sperm died before he was 30, or he is so arrogantly wrapped up in his own alternate reality that he would refuse to take responsibility for any child he would father (by you or any of his other FWB's, it would seem). So, content in his view of his own little self-defined world, he knows you are not a part of it beyond some sex romps that stimulate HIS glands, too. You let him; he does.
And you thought HE would be good FWB material?
On second thought, I HAVE decided who is more naive. So now you come HERE and tell us this tale of self-pity. No questions for us to answer. No advice sought. No sharing about any dilemma for which you might need guidance. Just a post on this board as a "crying towel." But I'm going to give you some advice even though you haven't asked for it via a question.
I know this is harsh, brutal advice, but here it is: IF you ARE pregnant, you need to grow up VERY fast and become a good, responsible mother who is strong and self-sufficient enough to provide for yourself and for your child. And you need to mature enough to know that a child cannot and should not be deprived of his/her father, so work out a way for your baby to have both parents in his/her life. If you are NOT pregnant, you need to GROW UP and realize that the realities of life are often in sharp contrast to the way we WISH things would be. Deal with life. And that starts by taking a good hard look at yourself and dealing with yourSELF.