Baby having cousins

I’m just posting to get this off my chest I guess. I am the only single mom of a BABY that I know of in my family. My cousin got divorced when her youngest kid was 10 years old. I was emotionally abused during and after my pregnancy. I had someone I couldn’t trust, no resources, and no one around (we moved to another state before I got pregnant). I had to do everything emotionally and physically alone with someone to watch the baby while I got 3 hours of sleep a night. Through that experience I realize now what type of man he is and I am at peace with what I had to do to get out and become a single mother of a 3 month old. My child is now 7 months old and has 2 younger second cousins, younger 1 first cousin (he is 5 months younger) and another second cousin on the way. My best friend had a baby too who is 4 months younger. I feel strongly about the new babies, I knew about them before they were born so I am not surprised. It isnt quite jealousy (or at least a mean jealous) because I am happy for the parents and all the family my kid’s having and going to get to grow up with. Maybe it is jealousy in the sense that I’m not getting attention and didn’t get attention while I was pregnant (no one threw me a baby shower or checked on me or anything, they only visited after the baby was born). I just feel so sad thinking of my kid growing up with another. I feel sad when I see my kid’s uncle being there for his newborn son when I have only my parents to help me (thankful for that but it isn’t the same as having an equal partner around). I am still in contact with his side of the family and my son’s grandmother is very excited to have 2 grandchildren close together and is talking about taking them on adventures together and stuff and she sent me a picture of the wagon she bought for them when they are older and I just felt so sad, I am not excited. I know I should be and I dont resent my child’s uncle, grandmother, or cousin but it just doesnt sit well with me. I know this could be a part of postpartum depression but it doesnt affect the care of my child, it just makes me want to isolate in my own bubble of my household compared to being around other kids. I am currently getting therapy but I cant quite describe the feeling so I find it hard to address it. Feel free to share your experiences, opinions, healing journeys. I think a little perspective may help me.