Yup, Sky has basically said it.
Anyone who tries to pull you away from a supportive relationship clearly has no clinical training in the therapeutic process!
You have been abused, disempowered, dismissed, devalued, ignored by waaaaayyyyy too many folks in your life; don't let another one do it to you now. If I were you, I'd not talk to this doc one second longer.
If your current therapist feels dbt may benefit you let him/her make a referral, (if he/she doesn't do dbt). I've an acquaintance who was doing dbt and at the same time continued to see her regular shrink.
By the way, are you seeing a clinical psychologist? I think your issues require at least that much skill. Not that all clinical psychologists are "good", but from the pool of clinical psychologists you can at least hope to find a good one. Whereas a CSW, no matter how "nice" he/she is, does not have the necessary training required to help you. IMO.
Your doc claims you have poor boundaries and are too dependent on your therapist, etc. Did you ask for his opinion or did he offer it on his own? You come to him for meds management, you've got your regular T to discuss boundary issues with. I'm quite turned off by HIS lack of boundaries in terms of where his job begins and ends, and just what his job acually is about. IMHO.
I've been seeing a T for nearly 7 years and it's normal to see a T and be "dependent" on one for as long as you need to. Part of the process is learning to trust yourself in taking care of your needs. And if being "dependent" on your T is something you still need then so be it.

Take good care!
Let us know what you decide,
Love,
9874