How do you put your child down? Almost 2 now

Around 1.5 we started to put him in his crib and give him a hug and kiss and shut door let him fall asleep on his own ( husband idea to wean him off us staying in there). This is done of course after night routine of milk, books, pj, brush teeth, prayers. Husband thought we should do this because he was starting to just make sure we weren’t leaving and it started to take a few hours to stay in his room ( rocking him at this age he would play and not fall asleep anymore). I miss being with him in there but I have a 6 month old I’m nursing. He always wants me though and unfortunately I haven’t stayed with him only once for nap time because my younger baby needs to breastfeed. He is going to be 2 next month my oldest and he always want mama to put him down and does not want his dad because he knows mama lingers when she can. I feel like an awful mama leaving him when he cries.

What do you all do ???? What should I do ? I miss him and don’t want him to feel abandoned by me. :( mama guilt and 2 under 2 guilt . I feel like attention on him was taken away a bit obviously with new baby but he loves his baby bro of course