I promise on all the chocolate in my house that it gets easier!
I was shocked at the change, completely normal to struggle
Have you got anyone who can help with DS1 for a bit - maybe a friend who could have him for a day so you can sleep.
Make sure you rest up whenever you can. Let things go for a few weeks,
Go to bed really early for a few weeks, it pays dividends.
Don't try and do too much,
Have you had panic attacks before? - I am a bit of an expert if you want any advice,
also keep talking to HV/DP etc about feeling down, may be blues but may be PND so keep talking, makes it much better.
It does get much easier.
I struggled loads with DS2 in someways more than DS1 (took me longer to bond - v normal apparently in second ones) but now it is easy (ish)!!! take care xxx