Should i restrict my son from being around her?

I have had custody of my 4 yo son since birth his moms seen him 3 times in the last year. My ex of 4 years ago is now a "butch" lesbein. Shes cut her hair really short and goes by the name "cole". I dont think this is healthy for my son to be around someone that has alot of mental issues especially with her uality. What should I do?