Being single is terrifying

A little over 2 months ago I went through a breakup where my partner of 4 years left me. Now that I've had a little time to reflect on this toxic dynamic and break and seeing her in the span of 2 months rebound off of multiple men, I've really started to realize it is over for good. And upon that realization I've also realized that being single is terrifying. I'm only 21 years old and am almost done with college now but ever since I was 13 I've been in long and short term relationships non stop.

while I understand I need time to be single and truly discover myself and heal past my anxious attachment and codependency to not keep repeating these same mistakes I can't stop to shake that feeling that I'm just missing out on life as long as im single and trying to build a sense of self respect and esteem while single feels impossible because it genuinely feels like I'll never truly love or care for myself without a partners validation and approval.

Does anyone have any advice on how to truly convince myself to stay single and learn how to love myself first before I try to devote myself to a new partner?