A feeling of sorrow, unhappiness, or guilt for a fault, wrong act, a loss, etc.:

I have no regrets.

Noun

v. 

To feel sorrow or remorse for (an act, fault, event, etc.):

He said he did not regret his decision to retire.

The thief said he regretted stealing the money.

He regrets that he cannot be here in person tonight.

Verb

Regret (Wordreference)

Regret + (not) -ing

We can actually use the verb regret(v) followed by a gerund to express regrets(n):

• I regret moving back to Spain

• I regret not having kids

Past regrets

​Students book, page 80

Should have + past participle

• To express mild regret or criticism regarding something in the past.

• We should have left earlier. There's a lot of traffic on the roads now.

• You should have spoken to her before you borrowed her phone.

Wish + past perfect

• To express a stronger regret about a past situation.

• I wish you hadn't eaten the last piece of cake. I was looking forward to it.

If only + past perfect

• To express an even stronger regret about a past situation.

• If only you'd tried it on before you bought it. It's too late to change it now.

Would rather / (sooner)

• To show mild regret or criticism relating to a past situation.

• I'd rather/(sooner) you hadn't told me the answer. I wanted to work it out myself.

• I'd rather/(sooner) not have overslept. It meant I was late for school

Student's book Page 76

Complete activities 4 and 5 about past regrets.