She gave him the heave-ho.

[Daruma]

Hello.

She broke up with him.

Can I say She gave him the heave-ho instead?

Thank you.

[PROESL]

Hello.

She broke up with him.

Can I say She gave him the heave-ho instead?

Thank you.

You can, but this makes it sound like she really wanted to put a great distance between her and him. It sounds like a stronger statement of rejection than simply saying "she broke up with him".

[Anglika]

If you are writing colloquially, yes.

[svartnik]

Hello.

She broke up with him.

Can I say She gave him the heave-ho instead?

Thank you.

Or you can say 'she gave him the elbow', 'gave him the push'.

[Barb_D]

Or you can say 'she gave him the elbow', 'gave him the push'.

Just a note: These would not be American expressions.
Another casual one: She dumped him.