HELP I’m pregnant with my ex’s baby

So I was with my first love for 5 years, and fell pregnant very young at the age of 15. (The second time I ever had sex). With serious disapproval from our families and the mess we was in, we begrudgingly decided it was best I had an abortion, and went through with it, which then caused our relationship to eventually end. Soon after my now ex, got with someone else and eventually had a child. His child is now three.

I am now 21, and recently started a new job, where it turns out my ex works. Which was a great shock to both of us! Because of this we spoke, and decided that we didn’t want things to be awkward! He is no longer with his child’s mother, and in the past month we have become much closer. Things ended up leading from one thing to another; and we ended up sleeping together on a couple of occasions.

Due to the busy Christmas period, we have drifted apart a bit over recent weeks. But today my period is 5 days late, and I have just found out I AM PREGNANT! I was on contraception, and know that neither of us wanted to have a baby together currently! I haven’t told my ex yet, and don’t know what to do! As I know last time we regretted our choice so much, and would of done anything to change it. But this time the situation is very different, and we are not in a relationship!

HELP!!