Is it normal my friend damaged me?

I was close with someone whom I even think I was in love with for a very long time. She was my first everything, basically a best friend who I came out to.
She was the closest person I have ever let in and I loved her so much. I'm 22f and I told her I had feelings for her which was about 9 months ago now & she didn't feel the same but claimed to love me.
Looking back in heinsight and our friendship, I do come to the realisation she was a user. My sister described her as toxic & my whole FAM could see this all except me. I tried to see the good in her because I knew she was damaged goods from her past & I felt a deep connection with her. She used to lie and did back stab me once, she hardly kept her word, was unreliable, unpredictable and broke my heart many times. Yet I stayed her friend for 6 yrs in hope she would change.
is it normal she ruined me, broke my trust. I find it hard to get closer to another female friend because of this. When ever I meet someone who I think is amazing, I always feel like they're gonna let me down or ditch me. IIN?
I have finally met someone amazing who turns out to be my cousin. I know for sure she's genuine because its not just words like with my last friend, but she shows it! She's thoughtful, sweet, compassionate, caring, funny, honest & reliable & actually makes an effort and for the first time in my life I feel valued.. She's everything I have been searching for in a best friend! I'm so lucky but part of me is afraid because we are becoming real close & I'm scared its too good to be true and I'm going to get hurt at any moment...
How do I get over this because I want to be close with a female again?