Well, sometimes when someone hurts us very badly, our first urge is to retaliate. Since it was a Scorpio that hurt you, they can be sarcastic and sure know how to hit where it hurts. Plus you have a Scorpio moon, so you are no slouch if you really want to hurt someone either. Cancer rising is how others see you, and it's a gentle and kind sign, sort of nurturing and maternal. But Cancers have long memories and thin skin at times, and you may take criticism too seriously. It's hard not to. But I think you have other factors here that will help you rise above it, and don't think anything is wrong with you.
Your Gemini Sun means you are intelligent and playful, interested a little bit in many subjects. You learn quickly and like to go out and surround yourself with people and new activities. You get bored easily, also a Cancer trait. The Venus in Leo is your love and social nature. You are very generous to others and a great host to friends. I think you are popular in your circle, and this and the Cancer in you is why you help others so much. Since Leo rules your nature in love, you want to be treated like royalty, and expect a lot of attention. The Scorpio moon adds intensity to your emotions, but I think the Gemini Sun can help you to get a little detachment or perspective on a relationship.
It's great to help others, but even friends and loved ones can take advantage of us, so learn to say "no." It's not easy. I think maybe a Scorpio sun person is too serious for you and won't give you the attention you need. A Libra or even an Aquarius would be fun for you, air signs, which go with your Gemini Sun and work with the Cancer rising and Venus in Leo. Don't be so hard on yourself, we all can't be perfect all the time. Sometimes we have to choose our battles and decide what to take seriously and what to let go.