Well to me, and I am by no means a tomato expert, it sounds like you did all the right things. The tomato plants looked great. Maybe some disease got to them? Maybe someone else can jump in with more experience of vegetables.
At least you were able to harvest some.
I tend to be a mother hen as well so I know how that can be. Lol.
You did your best and welcome by the way

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Hope someone else jumps in. The white roots sounds like they were healthy roots. That was my two cents.
There's a way to sterilize the soil for next year, but Iam not too sure about it.
Sending you good thoughts and fun gardening!!
😀
Mindi