I'm pregnant with me exs baby

Hi all I am no longer with my ex we had a 10 year relationship and have been split for 7 months we tried for a baby for 5 years and it didn't happen and it was all we wanted , we have been having Sex on and off since the split and I found out yesterday that I'm pregnant with which will be both our first, he thinks the best option is to abort because of the situation but I don't think it's fair when it was our mistake, he has said that he dosent want this but will step up if I choose to keep it but will be disappointed with me x really am stuck as I agree with him but at the same time I don't think it's fair to just 'get rid' of our baby I think we should take responsibility x it's hard because it's all I've ever wanted but not like this x any advice is appreciated x I know I'm gunna get some stuck for this