After baby

So we recently told my MIL that we are going to have another baby but it's still really early and we don't have our first appointment until Friday so still anything can happen even tho we are praying it doesn't but all my MIL can talk about is how after we have this baby that my fiancé needs to get fixed so we can't have anymore kids because she thinks we don't need any more and this really upsets me because we want at least one more after this depending on how everything goes he has one son who is 11 and we have one daughter together who is 19 months now we are having this baby so we want one more to make it even and we will have 4 all together but it's so upsetting when she keeps saying that because it's like she is trying to control what we are doing