I had a bull that died of cancer. Nikita..I too felt so guilty like you. I felt like i put her through hell only for her to die on me two weeks later. But in time you will realize like I have that you were just doing what you could to help your baby live. And you did right to let go when the time came.
I also just last sat lost my yorkie Tasha from a horse accident. I am so sorry for your loss..I know how you feel..It's so hard to love them so much and to have to let them go. I am here for you if you need me. YT has put a smile back on my face. I still have lots of bad moments but when I do I just come on here and get to posting..I have posted all over yt today off and on..It helps. This place will give you all the support you want and need.
I will pray for you and your family..and I want to say congratulations on your new baby and possibly future baby..