I'm lucky that my family love my hammies and even if they don't get why they at least pretend to. Whenever my dad is here he always wants to hug Thistle and I think he would be devastated if anything happened to her. My mum has never properly met my hams as she lives back in Cyprus but I know that she understands why I love them so much, our family has had pets since before I was born and knows that no matter how small the animal is, your love for it can be as big as it is for another human being.
The OHs family is very different though, well... his mother is anyway -.- She is one of those "its just a rodent" people (by the way if people use that you should point out that rabbits are rodents too and yet people seems to care about them much more) .
PP. your tattoo memorials are beautiful, people don't have any right to think you are an "idiot" for having it, it makes more sense than most people's tattoos and has a lot of love behind it. Regardless of how long hamsters live in comparison to dogs you still spend a good 2 or 3 years raising and taking care of them and that really is a long time when you look at it. I would do the same as you and stand my ground with an argument like this, you loved Honey, she was a part of your life and no one has the right to disrespect or disregard that. I hope that your mum comes around soon and apologises to you for what she said, we all understand how you feel though. I'm pretty sure everyone here has met at least one person who has used the "its just a hamster" line.
In the end though let's remember that we clearly are the better folk
After all, if we can love a creature so tiny we must have much bigger hearts than those who cannot even understand what an amazing creation they are.