There's no way it's about sending money. Read the text again:
I was thinking about what you said to me after we hung up, I'm so happy that you think of me that way. Thank you. Happy New Year my friend xo"
If your "friend" was lending or giving you money, you don't respond with "I'm happy you think of me THAT WAY" it means that he told her he thinks of her in some way - and very obviously in a sexual/flirty way. They are friends. They obviously talked on the phone and he obviously told her how he thinks of her. those are the facts.
The questions now become: how does he think of her? And why would that make her SO happy? My guess is that he told her something about how he can't stop thinking of her, that he really likes her, he can't stop thinking of kissing or sleeping with her. I bet she didn't respond right away. Probaably said "but you're married and we've been friends for XX years and I don't know how to respond to that." and the call ended.
Then - the text. She thought about it after they hung up and now she's SO HAPPY he thinks of her THAT way.