I think I share exactly the same experience and the very same thing helped greatly for me. I was just not diagnosed any postpartum depression but rather good old GAD.

After the birth of a son life changed 180 - no free time, no personal time etc etc. All you can expect. Less sleep, a lot of unknowns and anxieties. Again - expected. Less time with wife. Feelings of down, depression. Some anger problems. But it all looks like everyday life and everybody experiences stuff like that.

Then my father died. So I became "the man of the family".

Then corona hit. Then unknowns at work.

Then one day I was playing with my son and he hit his back and I felt so sick. However x-rays just nothing and he was just fine the next day. Life continues.

And one day I was just chilling and having some alone time and it all hit me like a train. Suddenly I thought I am gonna die. Somehow my heart will fail (my father had heart problems) and basically I could not function as a person. I just wanted that somebody would take me to the hospital or something and just care for me so if my hearts starts failing medics would be near. I couldn't work. One of the worst weeks or so of my life.

Of course my heart was just fine.

All these things were accumulating for some time already. The very same Lexapro helped me a lot. No side effects whatsoever. After a few months I felt like I was actually young again. Things started to improve both at home and at work. Anxiety is 99% gone. I am just so glad I got help. Actually I was forced to as I couldn't function.