I feel for you. Given you have a 4 year old and a near 1 year old, trust me, you are right in the hardest part right now. It gets much easier - nappies, buggies disappear, kids start fending for themselves and expressing themselves more and more. A good parenting adage - this too will pass.. They also get less cute, so don’t wish it away!
As they get a bit older, try and find some good reliable babysitters and make sure you have quality time out with your wife too, talking about something other than kids!!