Not surprisingly, the government rules for receiving both a civil service disability/retirement pension and Social Security benefits are complicated. There are two rules that can apply to your situation. One
is the Windfall Elimination Provision (WEP) that applies if you are receiving a pension based on your own years of service or disability. Under WEP, you are entitled to at least a minimum Social Security benefit. The other rule is the Government Pension Offset Provision (GPO) that applies if you are receiving widow's benefits. In this case, your Social Security benefit is reduced by 2/3 of your civil service pension. For example, if your civil service widow's pension is $600/mo, your Social Security is reduced by $400/mo. If your Social Security is less than $400, you will not get Social Security.
Without knowing the actual amounts that you receive, I cannot determine if you are entitled to a Social Security benefit. You should find an advocate who can help you navigate the system.
You asked about veterans benefits for widows. If your husband served at least 90 days on active duty and 1 day during wartime, you may be eligible for a widow's pension. There are 3 levels of benefits starting at $661/mo and going up to $1,056/mo. Eligibility is determined by your needs, e.g. are you housebound or do you require assistance from someone else?, and your income. If your income is below $661, you can get a pension that will make up the difference. If you are housebound or need assistance, you may be eligible for more money. Receiving this benefit will not affect your other income, including Social Security.