I've recently left my job in London to move to the Midlands. I have recently got a new job which I start on Monday. Im in Recruitment

Upon request of my P45 from my old employer 3 weeks ago I have not received this. In my time working for my employer I have not received any payslips (in 5 months, dodgy I know). I have asked on many occasions for my payslips for commission purposes.

When recently discussing this with my old employer he has become very bad tempered, after carefully looking into my finances I have seen that I have not been paid all of my commission.

My question is my reference, I start my new job this Monday, shall I put this company down as a reference? I am considering telling my new employer prior to Monday these above circumstance, is this a wise course of action?

I have the ability to provide other references also