I've been engaged twice...

I've been engaged twice. The first time to a guy I thought was perfect, I spent 4 years with him &  he proposed to me on Valentine's Day. I was so happy, until a month later when an old flame of his lit back up and he got cold feet. I moved out after he couldn't decide if he could stop his interaction with her or not. The second time was to a guy I only dated for 6 months but I still believed in love and after dating someone for 4 years and breaking it off, I figured the length of time you spend with someone before getting married doesn't determine your fate (especially considering my parents divorce after 23 years). Two months after he proposed to me, I found out he was having sex with a girl who was 6 months pregnant with another guy's baby. He left me when I confronted him about it with proof in hand and he's currently suing me for the ring I sold to pay the rent when he left. Now I've been in a relationship with a perfect guy for about a year, he is so caring and a genuine good person. He gets so excited talking about marriage and hints about it happening in the near future but I'm just over the thought of getting excited for it to not work out. I feel like a terrible judge of character and I'm actually kind of nervous. I feel bad that I'm being a downer about it but sometimes I can't help it! I feel so awkward being that girl who's been engaged twice and like people look at me like I make bad choices. I feel like I would feel more awkward to be engaged a third time, as bad as that sounds.