My feeling this is more about the ‘thoughtless behaviour’ than the art work?
You know the reality is that one day these things, EVERYTHING we own will be gone. Our house could catch fire, we could have a flood, we could be called to evacuate in an emergency and you wouldn’t pack the drawings; you would simply ensure everyone you love is safe and with you…
I can understand your attachment to these items, however Freya is still your miracle child and you don’t need the drawings to prove that; you only need to look into her eyes and hold her close to remember the miraculous event of her life.
Your issue, as I see it, is with the person who carried out the ‘thoughtless behaviour’ and it’s how you choose to respond to this that will determine the way you find closure. You can’t get the items back; they are now gone, but you still have the person who carried out the behaviour in your life.
I think the key to successful relationships lies in accepting that we do not always share the same values. Hopefully we share the ones that are deeply, deeply important to us on a soul level. But there will be other areas where we simply have to accept one another’s viewpoint. I am quite sure we can ALL find areas in our relationships where a clash of values is at play.
So you can express yourself without confrontation with something like “When [I discovered the drawings had been damaged] I felt [however you feel - my heart hurts / upset / ] because [I thought they had been carefully stored and taken care of]”.
That way you are expressing how you feel but without blame to the other person.
I had a similar thing with a drawing a friend did for DD when she was born. It was beautiful and I put it on the mantlepiece. One day DH was lighting a fire and he left the lighter going and put it on the mantel - well you can guess the rest; the picture caught fire.
Yes I was upset and hurt, I thought he had been bloody careless. But I realised on reflection that *I* should have framed that picture and put it on the wall where it couldn’t be harmed by a naked flame. Or *I* should have kept it in a room where there was no danger. Or *I* should have put it into an album rather than leaving it in a vulnerable place.
Maybe you could take back some of the responsibility for this incident. If these paintings were on a shelf in a garage how important were they honestly, truly, deeply? Wouldn’t those paintings be more valued framed and on the wall or beautifully presented in an album?
I realised that putting a picture as it was on a mantlepiece wasn’t exactly good stewardship; it was an accident waiting to happen. I also learned, when I went mad at my husband, that his value on the painting was nowhere near the same as mine; so there was a lesson learned for me…
I hope you feel calmer about things soon and who knows, maybe like I can with the painting my friend did for me, you might even be able to laugh about this one day 
All love
SC X