Would আপনি say the whole "evil stepmother" thing is too cliche?

Not at all. I think it's আরো realistic. It's harder to deal with someone else's kid and they tend to try your patience আরো than your own kid. And, of course, every time she sees the kid she's reminded of the woman her husband was with before her and kids always talk about their real mothers. Plus, stepmothers don't really have any sort of attachment to their step kid. Also, women are jealous দ্বারা nature so they don't like it when their man put someone else above them. When men have a kid before they meet their new girlfriend, their kid always comes first. Whereas if আপনি get married and a kid comes later, his wife remains his first priority. Does that make sense?

আপনি may want to change the "evil stepmother" into, for example, a cruel father অথবা an abusive mother, অথবা maybe a ex-boyfriend that betrayed you.

The "evil stepmother" has been a part of literature for centuries. I doubt any of us can forget Cinderella's wicked stepmother and stepsisters, অথবা Snow White's evil কুইন stepmother. That one was a real witch (pin intended).
I hope you're at least vaguely familiar with Harry Potter. আপনি see, Harry was very nearly abused. He was most certainly starved and neglected. I'm fairly sure that was the worst of it. Most of the damage was done দ্বারা Harry's aunt, uncle, and cousin.
Anyway, as আপনি can see, the evil stepmother is not a cliche, especially if আপনি decide to do it a little differently. As for why a mother would abuse her daughter, I refer back to Harry Potter. পিটুনিয়া was always jealous of the Wizarding world, ever since Lily learned she was a witch. Petunia, byh the time Harry arrived on her doorstep, denies that magic even exists. The Dursleys even go so far as totry and squash the magic out of him. They have called him a freak quite afew times. They've called him abnormal. And all just because of what heis, because of something he can't help.

I think it's আরো of a perennial trope than a cliche.
I think every story should have a few tropes here and there, just so they can be comparable to other works. আপনি can compare one use of the trope with another, causing people to actually think about your story.