In need of advice

So I just found out 2 days ago that I am pregnant. 3 weeks and 2 days. I was a little confused about how I felt because we weren't trying but I quickly became really excited, but my fiancé is not excited. He thinks we aren't ready for another child and wants to terminate the pregnancy. I'm heart broken and I don't know what to do. I want to keep the baby but I don't want him to resent me for it.