Old bad tenant now asking for reference and threatening us if we don't agree

Other

We recently had a bad tenant experience. The tenant failed to keep the property in good order, failed to notify us of problems at the property, and then in order to protect himself against potential loss of his security deposit, witheld last month's rent payment. He then threatened to sue us for damage to his furniture, became very hostile and intimidating. He left at the end of the tenancy, we were 1 month down in rent but kept the security deposit in lieu of rent. We then lost another month's rent whilst we had the property redecorated etc and found a new tenant. So all in all we ended up approx £1500 down what with costs etc.

Now, we receive a request asking us to give him a reference so that he can rent another property. He is now threatening that if we don't he will revisit his spurious claim against us for damage to his furniture etc and will 'send all the emails to all other parties' who I assume to be the agents he is now trying to rent through. Personally, I think that would have the effect of shooting himself in the foot, as any agent/landlord reading them would run a mile!
Should we just ignore the request or be honest and risk incurring his wrath again. He is a very unpleasant man.