Jodie Sweetin called 911 when her now ex-fiance stormed out of their house claiming he wanted to kill himself ... and it led to him going to jail.
Law enforcement sources tell TMZ ... Sweetin told them Justin Hodak was out of control after they had a nuclear fight during which she ended the engagement. She said Hodak threatened to kill himself and she was worried he'd make good on his threat.
Cops arrived and spoke with Jodie, who told them he had a gun in one of the bedrooms. Cops retrieved it, ran Hodak's rap sheet and found he was a felon, so possessing a gun was illegal.
We're told Hodak returned home later and cops were waiting. They slapped the cuffs on him and took him to jail.
Hodak bailed out a few hours later.
We reached out, but he had no comment.