How do I tell him

So my ex and I have been hooking up ever since we had my 5 month child , my whole pregnancy our relationship has been a disaster , but since we had her we have been in a good place for the most part . We don’t want to rush and get in a relationship bc we have a lot to fix individually

I am now pregnant with his second child I don’t regret at all bc we parent really well together . But idk how to tell him.