Final answer:
In the given lines, the word 'felicitate' means to feel or express intense happiness or joy. Regan is expressing her extreme delight in the love of the person she is speaking to and stating that their love brings her the highest joy and satisfaction, surpassing all other sources of happiness.
Step-by-step explanation:
In the given lines, the word 'felicitate' means to feel or express intense happiness or joy. In this context, Regan is expressing her extreme delight in the love of the person she is speaking to, and stating that she feels blessed and fortunate to have their love. She believes that their love brings her the highest joy and satisfaction, surpassing all other sources of happiness.