i usually am a guy online. no pretending, i simply am a guy when i am one. (except for those times when i'm not a guy, that's really awkward.) but i somehow ended up coming out before it was too late, and found a good enough support that i could manage to tell the people who might potentially get hurt. one girl heard it from someone who outed me to her because he's too religious to think it's ok for two girls to flirt with each other in a chat (i hate him a little for that). was fun to see her try to verbally kill him when he tried calling me anything other than a guy (she's one of the cutest girls i've known, too bad she lives in the wrong part of the world).
it's possible to find supportive people out there. it takes getting past the extreme vulnerability, risk getting hurt, at an early enough point in time when trying to get close to someone. some people might be willing to accept a man with a female body. you shouldn't say you pretend to be a man, you are one if you believe that you are. the only thing you've hidden is your past and current life as a female, pretending to be a woman because that's all you know how to do irl. not telling people about something like this when trying to get close to them isn't the smartest thing to do, but i don't think the lie wasn't without some truth.
if you feel like a monster, try to become human. humans are vulnerable, imperfect, weak, insecure. all kinds of things that are difficult to hide without becoming a monster.
you aren't too old to do a makeover on your body so you get a better house for your soul. 29 isn't old at all, i'm only a year younger than you and still planning to try transition. i'll be happy if i can start before i'm 30, but i won't bet on it. i'm glad i don't have too much dysphoria related to my body, i can afford to take my time.