What’s Adele’s “Send My Love (To Your New Lover)” song meaning?

Adele really seems detached in this song when singing about her ex-lover, wanting to transmit that she’s happy now as she has been set free by him / he broke up with her. I was waiting for a happier song from Adele.She says that they “ain’t kids no more” and the ghosts from the past must be forgotten totally.

We’ve gotta let go of all of our ghosts

We both know we ain’t kids no more

Even though she tries to seem happy, I think she suffers and she struggles to stay strong (Gloria Gaynor’s I Will Survive keeps singing in my ear already). Adele wishes that he has a better life without her (Send my love to your new lover, Treat her better), while she will find someone that deserves her (I was too strong you were trembling, You couldn’t handle the hot heat rising).She underlines the fact that he was limited and couldn’t keep up with her:

Baby I’m still rising

I was running, you were walking

You couldn’t keep up, you were falling down

I don’t know if Adele talks about her being limited by him in LOVE or in CAREER or something else. She knows better.She mentions “treat her better”, his new girlfriend, so it’s very clear that she was not too happy, so the break-up could be a bless in the end for her.