It never made sense to me why Tony wrote the movie, but after rewatching the series, it finally clicked..

In Season 4, Episode 23, after Ted was left at the altar, Tony visits Ted's apartment to offer him a job, supposedly to make amends after seeing Ted's sadness. However, I think Tony did this because Ted’s apparent ease in moving on irritated him. Tony couldn't understand how Ted could move on so quickly, so he offered the job to convince himself that he had won and Ted was left miserable. This also explains why Tony broke up with Stella after meeting up with Ted.

Tony was so bitter about not being able to gloat over Ted's misery that he had to write and produce "The Wedding Bride" to satisfy his ego by casting Ted as the villain.

Finally, "The wedding bride" makes sense.

Edit: Forgot to mention that I came to this conclusion when I watched the scene between Ted and Tony, I observed how how much he was trying to gaslight himself or Ted into thinking that Ted was sad and miserable when they met him previously. It was as if he was trying to convince himself that Ted should be broken and miserable which was the opposite of what he saw.