PR questions. Please help

Hi everyone
I have a question regarding the permanent residence.
My and my husband (Bulgarian ) came in his country at the beginning of 2011. Soon after he received his yellow card, working self employed and I received the blue card in dec 2012. I believe that this blue card is for dependents and with it I was employed. In 2014 we separated. We still have separate lived to this day. We don't really keep in touch.
My questions is when should I apply for permanent residence?
If I received that blue card and it is for dependent (although i have been working since and i am self sufficient) wouldn't that mean that my permanent residence should be gained again as dependent?
These blue card have stopped being used in 2014, but are they still a valid form of documentation as resident? It doesn't have an expiration date on it. Also, on the back it is stated that after 5 years of holding that card I could apply for permanent residence.
Would that mean as a dependent, and my ex being a sponsor?
I am sure he would not help me in any way with anything.
What is the best way to apply for PR?

Sorry for the endless questions.
Also, when at some point I received working tax credits for 3 months. Would that affect my application.
I feel completely lost in this complicated story.

What are your nationalities?

In which country does your husband reside? And where has he resided for the past five years?

Both from Bulgaria. Husband has been in the UK since 2011

Up. Anyone please?