I think Mobius is right, there has to be a clear drawing up of limits which are respected and absolute. Hard limits that are NOT breached. Behaviour in front of your child would absolutely count here, but also whatever YOU felt should also be classed as a non-negotiable limit. In your situation you must be able to stop this behaviour at any time, have you discussed the importance of safe-words?

The belittling and direspectful behaviour that you are shown is completely unjustified and does not belong under the umbrella of BDSM, your partner must also be made to see the difference between the two - Abuse and BDSM.

There is a very definitve thread on Abuse vs BDSM somewhere on this site - a search should get it for you very quickly, you may do well to have a read and bring it up with your partner.

I hope you can both find some balance and establish a BDSM relationship that does not involve your child or abuse to yourself.