The legal battle over the sexual abuse allegations against “X-Men: Days of Future Past” director Bryan Singer has turned vicious.

Singer’s lawyer, Marty Singer (no relation), has issued a blistering attack on Michael Egan’s attorney Jeff Herman and warned that he will sue for malicious prosecution.

“You seek to preen for the media in an effort to solicit new clients, ultimately looking for a payday for yourself,” read Marty Singer’s letter. “You have now resorted to lying to the public concerning your actions, including your false statements to the media this week to the effect that our client has refused to accept service of your earlier lawsuit on behalf of Michael Egan.”

Herman has filed five sexual abuse suits in the past two weeks and held three news conferences detailing allegations that Singer, Gary Goddard, Garth Ancier and David Neuman were involved in a ring that coerced underage teenagers into sexual activity. Egan is the plaintiff in four of the suits, and an anonymous British man filed the fifth.

“On behalf of Mr. Singer, I am hereby demanding that you immediately dismiss, with prejudice, the Egan lawsuit and refrain from refiling the ‘John Doe’ lawsuit that you filed against him,” the letter said. “If you fail to do so, then you will be exposed to significant liability.”

Herman responded by reiterating his pledge that he will press on.

“This is a critical time in these cases because this is when I typically see the strongest pushback,” Herman said in a statement to Variety. “I made a commitment not only to these victims but to all victims who allege to have been harmed by Hollywood predators that, if based on the facts, I have a good faith belief in the merits of their claim, I will not be deterred by threats or bullying in my quest to shine a light on this darkness and seek justice for victims.”

Herman has promised that more suits are coming and said specifically that one would involve another “sex ring” operating in Hollywood. “I’ve heard from victims about very recent claims of being sexually exploited in Hollywood,” he said at his May 5 news conference.

Herman has also insisted several times that he won’t be “bullied” and noted that the pushback to the suits is designed to prevent other potential plaintiffs from coming forward.

Herman said on May 5 that the pushback reminds him of the early days of the clergy sex abuse scandal. “There was complete denial,” he added.

Marty Singer also noted that Herman had been suspended for 18 months by the Florida Supreme Court in 2009 for investing in and controlling a business competitor of a client and failing to tell the client he had done so.

“Perhaps we should not be surprised that you have made such gross misrepresentations given your suspension by the Florida Bar for engaging in conduct involving dishonesty and deceit,” Singer said. “You only care about seeking publicity for yourself and attempting to revive your career after being so publicly and embarrassingly suspended from practice.”

Singer also blasted Herman for filing a sexual abuse lawsuit against Elmo puppeteer Kevin Clash, which was dismissed in July by a New York judge due to the expiration of the statute of limitations.

“You have demonstrated a pattern of filing legally deficient lawsuits,” Singer wrote. “Your repeated failure to properly investigate claims before rushing to the courthouse and then hosting press conferences is inexcusable and rises to the level of sanctionable conduct.”

The letter also asserts that Herman is seeking to promote a documentary film — which prompted another warning from Singer.

“It is evident that you want to be a celebrity by being featured in a documentary that will face significant legal challenges by my client if any malicious and/or defamatory statements are communicated therein,” he said. “There is no legal privilege for such conduct. Your disingenuous behavior will be fully exposed to the public and your true motives will be revealed.”