It hurts my heart

So I guess maybe I'm just posting to vent to see if it makes me feel better, and I'm posting anon because I feel terrible about my own feelings.

So to start with I have 3 beautiful little girls. Ranging from 7 to 4 months. I love them all immensely, but I've always longed for a little boy. With my newest addition i went through quite a bit of gender disappointment when we found out we were having another girl and when she was born a heavy set of postpartum depression, so we got off to a rocky start but by God is she the most beautiful little girl I've ever seen (which I say about all my girls lol but 😱 perfection).

Anywho, the weekend that I had her my SIL and BIL found out they were expecting their first together (she has another little girl from a previous relationship) So a week ago they found out they're having a little boy...I'm happy for them I am...but my heart also aches so immensely when I'm around her or see anything she posts about him. I'm sure that seems so selfish, fore I have 3 beautiful children while some struggle to even have one, but I just feel a pain in my heart so deep and I just simply don't know what to do about it. At this point I struggle even being around her right now without wanting to cry my eyes out.

Well thanks for reading if you chose too. If you have advice I'm all ears, if not thanks for listening.