Huda Mustafa's BF Louis Russell Says His Ex Is Keeping His Son From Him

3:36PM PT -- A source close to Nicole tells us … Louis also agreed not to allow Huda to meet their son and that Nicole knew Huda was unstable and insecure from the very beginning.

We’re told Louis was living with Nicole and their son, and when she asked him not to allow someone who he just met to track their son’s whereabouts, Huda "went crazy on him." According to our source, after everything happened in February, Louis told Nicole she was right the whole time, down to her asking him not to let Huda know where his and Nicole’s lives.

Our source tells us Louis stayed with Nicole for the whole week after this incident. We’re told Nicole made sure Huda never met their son and that Louis encouraged Nicole to file the restraining order and sent Nicole texts between Huda and him.

Louis Russell was on "Too Hot to Handle," not "The Ultimatum" ... but he says his ex gave him one concerning their kid -- break up with Huda, or you can't see your son!

In court documents, obtained by TMZ, Louis claims his ex-girlfriend, Nicole Olivera, has "unreasonably" cut off all contact between him and their son, Luka ... despite Louis saying he agreed not to have his girlfriend Huda Mustafa with him during their visits.

According to the papers, Louis alleges Nicole is using Luka "as a bargaining chip" and has threatened to move out of state. He expands further ...

Louis says, "I am seriously concerned that she will make good on this threat before she is served. I fear that she will move Luka, and I will have a hard time finding our son and being a part of his life."

According to Louis, "Nicole has threatened to move before and did so when we were in the UK."

Because of this, Louis is seeking an emergency order from the court to give him joint legal custody and a concrete parenting and custody plan that allows him time with the child.

Remember ... Nicole got a temporary restraining order after claiming Huda forced her way into Nicole's building last month. In response, Huda posted a message yesterday, writing, "I'm aware of what's being said and it's not true. I'm handling everything the right way by letting legal take care of it. I appreciate everyone who continues to support me."