I like your post and the last line is really key.

When we are young we hear versions of this (e.g. "have to love yourself first") and despite the trite or pithy phrasings of it, it contains a truth.

We shouldn't conflate not being partnered with being alone. There is so much else socially we need to cultivate whether it is family, friends, coworkers, community, or just being in the world and talking to a stranger.

If all this feels sad or empty because of the breakup, that's ok. FEEL IT. The only way out is through. Feel it, don't numb it, try to find gratitude for the pain because it will lead you to where you need to be. The darkness and the light, etc.

And when you arrive in a place where you no longer feel you need a partner to complete you or make your day feel meaningful, is the time you are ready to have a partner again.

One shouldn't hate too much on self-improvement books. There are tons of good ones out there. Inversely, there is a lot of garbage psychology and philosophy material out there as well.

The key here should be to do research. Thoughtfully pick out what you should read to expand your mind in a positive direction.