Rejection just really scares me
Soooo that's why you decided to start rejecting him, right? Because you would rather destroy your relationship than get over yourself. You're scared of rejection, so you become the rejector, in order to do what? Destroy, obviously!
Can't do sexual stuff with my bf :/
Yes you can, you totally can, you just won't. Because you've made a decision not to do it. Not because of inability, but because of a free choice. The choice you made to reject him, to deprive him, and to destroy your relationship. You made this choice. And now you're lying to yourself, and lying to us, that you "can't" have sex with him. There is no "can't" in this life! There is only "won't". Everything is a choice, and you've made yours.
Nobody can help you. You can go to counseling and whine to your therapist all day long how discoloured your skin is, and your therapist will gladly charge you their fee to listen to your bullshit for years and years on end. It's not going to help. Why? Because everything is in your own hands. All it takes is a flick of a switch, a decision in the mind, just looking at yourself in the mirror and saying "What I am doing is destroying us. I am destroying us. My bullshit is destroying us, my insecurity is ruining our love, I am allowing, no, I am actively changing this relationship from bad to worse to shit. I am the kind of person who destroys love, that which is most sacred, because of a little funny colour on my skin."
Try that - look at yourself in the mirror and tell yourself that. And if you are still unable to experience disgust with your own choices, and the effects of your own choices, the choice to be so silly, if you cannot even feel repulsed by what you've become, then you are truly beyond help.
Your skin condition is not what makes you ugly, nobody gives a shit about it. What makes you ugly is the complete lack of confidence, self-esteem and the utter desperation your harbour in your heart. Good luck finding a therapist who would tell you this simple truth. And why would a therapist tell you the cold hard truth to your face like that? They want your fees, and they want you to keep going to them for as long as possible. A therapist cannot afford to be so brutally honest to you like an anonymous internet stranger.
Can you change? You totally can! However, it's not a matter of whether you can or cannot do it. It is a matter of whether you will or will not do it. It's about will, not about ability. If you have the will, ability will improve with time. If you don't have the will to fix this, it will be un-fixable. And when the will to change is present, even the seemingly "impossible" things cave in with ease.
You're being too soft on yourself. Seeking sympathy, understanding and support only makes you weaker, more insecure, uglier. Maybe the time has come for you to finally grow up and realize that what you do has consequences and that all that happens in your own life is your own responsibility.
Here is another grain of truth that no therapist will ever tell you no matter how much money you pay them: Not all feelings are important, not all thoughts must necessarily be entertained, not all intuitions or gut feelings should be trusted or given significance. You are ascribing importance to insignificant issues. By doing that you are putting the truly important stuff on the back-burner. You're being short-sighted and yes, silly, by paying more attention to some superficial visual flaw. You're just like a person who breaks up with someone because they can't handle the way their partner chews with their mouth open sometimes. Or like the person who quit their job because sometimes the coffee maker is all out of coffee. Exactly the same - superficial and not very thoughtful. You just do it because of an insignificant flaw in yourself, other superficial people do it because of their partner's insignificant flaw. Because you're also self-absorbed. If you could see an inch beyond your own nose, you would have noticed already that your partner also has flaws, and everyone else around your also does. And your flaws are no bigger and no more significant than everyone else's. What makes your own flaws seem bigger and worse than others' is your own self-absorption. Your own little wart is a disaster, a catastrophe, a cataclysm of cosmic proportions. Why? Because obviously you think yourself the center of the universe, and skin discolouration ON THE CENTER OF THE UNIVERSE'S THIES is a pretty big deal!
So yeah, here is a third truth that no therapist will ever admit to you because your fragile little feelings will be hurt by hearing it, but here it is - people of extremely low self-esteem, those self-deprecating types like yourself - they are the most self-absorbed, egotistical, me-me-me types of persons. The only difference is that you like to think bad things about yourself. It doesn't matter though - you're still thinking about yourself only, even if it is bad stuff. All of your attention is on yourself, your own flaws, how bad it is to be you, you-you-you. And while you poison yourself with constant preoccupation about some minor skin issue, you're turning a blind eye on your partner's suffering. And that is evil. Even if you "didn't realize it" and even if you "never thought about it". It's still evil.
TL;DR: 1. True ugliness comes from weakness, desperation and self-defeat. True ugliness has nothing to do with how you look physically. It's much, much worse. 2. To give importance to every single though and feeling is madness and stupidity. People sometimes get crazy irrational thoughts. Don't feed such thoughts with attention or they will consume you. 3. Self-deprecating low-self-esteem types are the worst egocentrics. Believe it or not, the world does not revolve around how horrendous a zit you have on your face today or how bad of a hair day you're having. It is cruel and evil to be destroying a perfectly good relationship because you insist on the importance of your minor flaws.
Feel free to start losing your mind now.