Does Gertrude share in Claudius’s guilt? I need quotation and explanation

In the end, Gertrude most certainly feels a sense of guilt. Prior to Hamlet's death, she seems unable to discern any kind of malice or deception in those she loves, whether she is truly that naive, or whether she refuses to see is another question.... one we are left to ponder. When she comes to the realization that the wine she offers Hamlet is poisoned, however, she warns him not to drink it and drinks it herself.

No, no, the drink, the drink,--O my dear Hamlet,--

The drink, the drink! I am poison'd.