>>112145NTA but since you're the real you in the texts and only your appearance is a lie, I think if he's this in love with you tell him that the real reason you tried to break up with him is the fact that you don't look like your pictures but it's really you otherwise. Catfishing isn't honestly that uncommon and it's understandable that in this age of filters and Instagram models one would be self conscious enough to catfish even if it is wrong, it's rather empathetic.
Since this is online only still, you can even wait to reveal it once your self esteem is better and you're more ok with the possibility he is more upset with your looks than imo he should be for someone this in love with your personality. Then you can reveal it knowing worst case your relationship is simply over, best case you're still together and you're more free in conscience and can still be yourself around him and be at peace whatever the option but knowing the worst isn't so bad, and the best is simply wonderful