question for you lovely ladies

I am 36 (hubby 40) and married for 16 1/2 years. We have 3 sons, 21, 8 and 6. I claim the 21 year old as my own but he is my husbands from his first marriage. Anyway, we were and have been trying for another to complete our family but we found out last week that our 21 year old son's ex-girlfriend might be pregnant and is due for her first doctor's visit on 5/5/17. At this point I feel devastated like we shouldn't even try anymore. I had an ectopic in October of last year so I would have been pregnant now if all would have been ok. How can we expand our family when we might be grandparents soon!