Identifying Paradox and Oxymoron in Literature

In the following excerpt from a classic novel, the author employs various literary devices to convey complex emotions. Sequential phrases suggest conflicting feelings, highlighting the protagonist's internal struggle. As you read, identify the phrase that serves as an example of an oxymoron or paradox:

"As the darkness of night enveloped her, she felt an overwhelming sense of joyous despair that left her breathless. With each tear she shed, she smiled wryly, embracing the bitter sweetness of her memories."