What to do ?

My current boyfriend and I just found out he has a baby on the way. The young lady is 7 months pregnant and she waited to tell him 3 months into our new relationship . His love and affection towards me did not change but now she is jealous and wants to ruin him(us) and now he is very stressed because he wants to the right thing which is be there for baby but not be with her because of same reason why they broke up, but I am very worried and insecure that when the baby gets here that he we leave me for his family . What to do when I have been in a situation like this and got dumped for his family ?