Oh I'm so sorry and know what your going thru, these things happen if only to make it better for the ones to come. I know that's hard to accept and yes you will beat yourself up for a long time. The price was high for this lesson...BUT you have to let it go and chalk it up to experience. No matter how hard it is to do.
I feel your pain and feel so bad for you. You must let it go...in time it will heal but there will always be a scar and empty spot in your heart. I too share that guilt and have made the best of a bad situation.
Good luck with your schooling too.
If you ever need to talk, I will listen. Ferret friend, Barrett