The pair tied the knot in 2001 but at the time she was still married to Carlos Marty, who she wed in 1993, and the Guns N' Roses lead guitarist, who filed for divorce from her in December 2014, is said to think she's ''a bigamist'' who has no right to a share in his earnings.
According to gossip website TMZ, the 51-year-old rocker wants a judge to say he wasn't married to Perla, who is said to be looking to receive 50 per cent of his earnings during their 13-year marriage.
Perla, 39, and Carlos divorced after one month of marriage but it later turned out their forms weren't filed properly.
Despite this, she claims the pair hired a lawyer in 2009 and a judge finalised the split and made it retroactive to 1994.
Perla thought she was a single lady when she married Slash but the former couple discovered she hadn't properly divorced Carlos when they applied for dual citizenship for their son Cash, 10.
However, the publication claims that a ''putative spouses'' law states that if two people believe they are married but there is an issue with the documents then a judge can treat them as wed and divide their earnings appropriately.
Slash - who also has 12-year-old son London with his estranged wife - is said to have cited irreconcilable differences and listed their date of separation as June 15th in his legal documents.
The guitarist - whose real name is SAUL HUDSON - has also requested joint physical and legal custody of their sons.
It's not the first time Slash has filed for divorce from Perla, who is also his manager and runs all his companies, as he did so in 2010.
But he withdrew the petition just two months later when they managed to work things out.