Your wife may be eligible for a survivor benefit. If you have a qualified pension plan your wife would have needed to waive her eligibility for a survivor benefit.
The bottom line is that you need to check the documents for your specific plan. I would contact your previous employer's HR department to start.
If this is from a pension, there is a survivor benefit for your wife if you specified there to be before you began recieving your monthly pension checks. Find out how you set this up by calling your pension plan administrator, there will be a phone number on any correspondence that you have received from them.
If this payment is from a monthly withdrawal from a 401(k) or IRA, there is no payment for the surviving spouse unless it is coming from an annuity that you have set up to pay for joint lifetime. She will just get whatever is left at your death.