Eleny, I am going through my own pain right now and I completely understand how you may be feeling. I found a journal entry dated 6 months into the relationship where I completely rationalized the actions of my (then) verbally abusive partner. If I had followed my gut I would not have ended up financially drained, mentally in shambles, cheated on and healing from a fractured rib a year later.
Follow your gut. Your instincts are usually right because they are prompting you to look out for your best interest. If he felt it was okay to lie to you about the person before, he will likely lie to you again about something else that is just as important. Apologies are great but they mean nothing after the fact, especially if he did not come clean himself. Your partner should be telling you how great your boobs are, no matter the size. Don't let anyone make you feel inferior FOR ANY REASON.
Being alone can make you feel sad, I won't lie. However there is a certain magic to the freedom of being single. For one thing, you have the freedom to choose again. To take care of yourself, be comfortable being alone so that you know that you won't end up with another toxic person just because you want to feel love. This is my personal opinion, from my experience. People like that will only continue to take advantage of your kindness and your desire to love.
Be prepared for rage when you try to break things off. Especially if they keep saying they don't want to lose you. They may try to belittle you or say that you won't find anyone else like them, or anyone else who would put up with you just to make you second guess yourself. They may even threaten to harm themselves if you leave. Do not let this deter you because the truth is that they will get up, dust themselves off and move on to finding their next prey. It's happened to me multiple times in my short 24 years of life and it's only this last horrible relationship that drove the point home for me. Don't let it get to the point of no return before choosing yourself - the PTSD from the trauma is not fun at all.
Believe in yourself! You can do it
Sending hugs, strength, kindness and compassion.