Misuse vs. Abuse vs. Ill-used

Misuse
Using something in incorrectly,carelessly and in a wrong way.

- In some cases pesticides are deliberately misused.
- He misused the money, it belongs to his club but he used it for himself.
- You're protected instantly if a thief misuses your credit card.
- He lost his job for his misuse of money which belonged to the company.
- Measures must be taken to prevent confidential data from being misused.

Abuse
To deliberately use or treat someone or something,especially power or authority for the wrong purpose or for your advantage.

- The minister was sacked for abusing power for his personal gain.
- He showed how the rich and powerful can abuse their position.
- He's well known for his abuse of power.
- She abuses her health with all these late-night parties.
- Several of the children had been sexually abused.
- He was arrested by the police for the drug abuse.

Notice that the difference between the two misuse and abuse is that you can abuse someone but can not misuse someone and also the adverbs such as sexually,physically and emotionally can come with the latter.

Ill-used
Of persons, taken advantage of,exploit someone :

- All the prisons were ill use.
- I have the feeling of being ill used again.

Ill-used is mainly used as an adjective.It means the same as use which is more commonly used than ill-used.

See also disused and unused.