Unless you got a divorce before you became a widow and before your spouse died then you as a widow are considered to be still married.
However when you're a widow you can still legally marry another person even without being actually divorced from the spouse that died.
Since you'll be able to prove your spouse died then you can legally be considered not married anymore but in reality once you're married and don't get a divorce you really are still married even when your spouse dies.
Basically you as a widow are still married but haven't married yet again but as a widow you can still marry another person if you desire.
It's perfectly okay to marry again even when your spouse dies and some spouses have told their other spouse that if they die that they would be okay with them marrying another person again.