[QUOTE=marie4567;6406015]
Hello Marie. Wow you are very tough on yourself!!! I am curious where those critical thoughts are coming from? Are they coming from your own mind or is your bf saying or suggesting some of those things to you? How were your parents growing up? Did they criticize you a lot? Were they supportive? We typically learn how to treat ourselves starting in childhood...based on how our parents treat us. Did these critical thoughts of yours start during your relationship with your bf or before? I think that's really important to think about.
You mentioned that you are 20 and he's 36. How do you feel about the large age-gap? I'm not moralizing here...I think it's up to consenting adults to decide if they're okay with an age gap or not. One thing I wanted to mention. When I was about your age, I was in a serious relationship with a guy 10 years older than me. It started out wonderfully and we fell in love but over time I realized that we had a power differential...it did not go well and I ended the relationship. I am NOT at all trying to imply that's what will happen in your relationship. I just think it's good to keep in the back of our minds that any major difference such as income (low income / high income) or age gap can lead to a power differential which can create problems.
Your post focused a lot on him and what's right for him. What about you? What do you need or want? You sound very unhappy with yourself...do i have that right? If you are open to it, I think you could really benefit from talking with an experienced therapist to focus on your self-esteem etc.
Please know that you are "good enough" whether in a relationship with this man, or someone else, or nobody at all. You are a precious being in the Universe. Your worth is intrinsic and not based on other people's opinions or feelings about you. Speaking from my own experience, I believe that happiness and love start with the Self. We must learn to be loving and patient with the Self. We can share our love and joy with others but we cannot look to others to create it for us...nor can we create love or joy for someone else. Does that make sense?
You deserve a great big safe
By the way, I am impressed by you. You sound like a very intelligent, thoughtful, and introspective 20 year old. The world is better with you here.

Please go easy on yourself, will you? Take a look at Inner Child theory. It may be very helpful for you.