I think there will be a lot of benefit in working through these feelings with a T.

Is it possible that having a fwb is messing up your whole perception of love/sex/relationships? Like it is one big muddle...?

I personally cannot do the fwb part, as I know it messes with me too much. If you are getting some of your needs met, you're happy to keep this kind of relationship going, but then miss the other aspects that you need fulfilled. Is it possible to let fwb become your partner? Accept his love?
Or is one of the others the right ONE...?
Of course you are worthy of being loved, and if you doubt it - you just need to look behind you to see that there are 3 guys hot on your heals (Yes, we need to question if their motive is love or sex, but that's another conversation altogether...)

Please don't beat yourself up - you are worthy of love; you are a uniquely created human who has a perfect match.
There's no-one on this planet that is not worthy of love, least of all you.