The former Hollyoaks actress, 23, lashed out on Twitter after she was pictured kissing Ex On The Beach star Jordan on a night out this week.
But retaliating via a lengthy Twitter post, she insisted the pair were just friends who'd kissed on a night out – and got a dig in at ex-boyfriend Jeremy as well.
Steph wrote: "Number one, was on a night out. Number two, been through more than you will all know. Number three, it's okay for Jez to sleep with someone six hours after breaking up but after lying and hurting me (sic).
"But I can't do the same after all he's done and only a kiss. #tasteofyourownmedican (sic)."
Stephanie went on to say: "Number four. Me and Jordan are FRIENDS who just had a good night out and finding myself again. Number five, it's all caused through someone's actions… but CERTAINLY NOT MINE!!! Don't think because I smile I'm not mad."
She then added: "I'd never slag Jeremy despite all but we're was he when I needed him...? #neededme #tryingtomoveon #future (sic)."
We have contacted Jeremy's rep for comment.
Stephanie and Jeremy's tumultuous relationship has rarely been out of the headlines since they met in the Celebrity Big Brother in January.
He admitted sleeping with another woman, but denied it was cheating as it happened after his eviction from the house, while Steph was still inside, and before they were dating. He also said he wasn't sure what would happen between Steph and her then-boyfriend Sam Reece at the time.
Jez vehemently denied other allegations of infidelity.
Their most recent split happened at the start of May, when they parted ways for a fourth time. Steph denied reports she'd gone AWOL and hooked up with another man, and it all got confusing as Jez then tweeted "love you" at Steph before deleting it, and she went on Irish radio to say she'd been madly in love with him but there wasn't room for her in his life.
But she also said: "I fell out with my family, I lost everything, I didn't have anyone. Then he accused me and left me… I gave up everything for love really, just to be heartbroken. I just feel like I've got no-one, and the one person I needed was Jez."
Jeremy, meanwhile, posted a cryptic Twitter rant this week but did not name who he was talking about: "You meet some very evil vindictive people out there that think they can pull wool over your eyes. I won't say, I'll let use see in time.
"Lied to for months while all her friends worked on a little project, enjoy your new house guys, bravo S&S."
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