Brian Walshe — the Massachusetts man on trial for allegedly murdering his wife Ana — is a narcissistic sociopath who reveled in watching cheating wife porn after he suspected his spouse of stepping out on him … according to Dr. Phil.

TMZ caught up with the famous doc amid Walshe’s murder trial … and Phil walked us through Walshe’s penchant for browsing Pornhub looking for smut films depicting a cheating spouse, which Walshe suspected Ana of being before she disappeared in 2023.

Walshe has pleaded guilty to disposing of Ana’s body and misleading police … her remains have never been found. Prosecutors charged Walshe with Ana’s murder despite his denials he killed her.

Today, on day four of Walshe’s criminal trial, William Fastow testified he was having an extramarital affair with Ana before she vanished … Dr. Phil says someone like Walshe uses his laptop to search for XXX-rated movies to reinforce his “victim” status and plot his revenge.

Dr. Phil explains narcissists like Walshe can only see their point of view and can’t handle rejection, “so they need to wipe everything off the board.” Phil also says Walshe wouldn’t sleep with another woman to get back at Ana. Instead, Phil says, Walshe would be of the mindset … “If you don’t want me, you’re not going to have anybody.”