I don't think Tisha was lying all together about Martin. Both Tichina and Carl Payne have said she was not lying. My take on it is Tisha and Martin used to mess around, and then she got with Dwayne Martin somewhere down the line. Couple that with Martin's alleged mental health issues around the time, and yeah. I'm guessing the mental health aspect is why they are both able to forgive and move on from it now.
I don't think they were necessarily messing around, but I think that Dwayne Martin was the catalyst for all the chaos. Tisha mentioned that Martin was the first one to reach out to her when the divorce was announced. Also, Tisha and Tichina are still tight. If I was being sexually harassed on the job (and I have been - it's HORRIBLE), I would
never forgive my homegirl for sticking around.
My guess is that Dwayne probably took Martin's off-color, on-set humor towards Tisha personally and was on some "keep my wife's name out your fukking mouth" shyt. Martin, being Martin, probably escalated that shyt to a thousand, and Tisha was in the middle. Martin didn't understand b/c that's how shyt had always been like before Dwayne showed up, and it all went downhill from there. A shame, too, b/c you'd be hard-pressed to narrow the best Martin moments to just 10 - but NONE of them would come from season 5.
And Gayle must be on some other shyt, because Tisha shined on My Wife and Kids. She's never not worked.