root rot?

[kforsythe]

Hello! Please help! My husband got me an Oncidium for Mother's day and I think I've killed it.
I first noticed the psuedobulbs shriveling and so I started watering it more often and now two leaves have turned yellow. I pulled it out of the bark and noticed the roots (particularly the one that is yellowing) are brown and mushy while the other bulbs roots are more white and dry. Not totally sure what I am looking for here. The bark the orchid is in does not feel very wet to me, just barely damp. I started to trim the brown roots, but stopped fearing I would make things worse.
the more I read on orchid care the more confused I get.
Can someone please help me?!
thank you!