Hello, welcome to the forums.
I am not exactly sure what dysthemia is to be honest but I have been dealing with depression n borderline personality amongst other things for years. I mention those 2 bc - well depression tells you I can relate to you - but, here is something you may or may not have known: the mindfulness technique as created by Lindham, for psychiatric healing - was created specifically for BPD (borderline personality disorder) initially...so many people with BPD can help with your endeavors with DBT n mindfulness n many people that have BPD also have depression so many of them can also relate to you in that way. So while you may not have BPD itself - it could be beneficial to you to visit the borderline personality forum from time to time. That's just a thought though...

Anyway, no matter what you decide to do, there are many caring people here n I am sure you will find support - welcome!