<human>: My mom married Chase's dad when I was 6. Since my own dad was no prize, I took to my stepdad right away. He showed me more of casual kindness than genuine interest, but I adored my new family.

Especially my new stepbrother. He was 8 years older than me but very kind. Always brought me little trinkets and made sure to include me. Big things like teaching me to ride a horse and small like bringing me candy from the store. But it was really cemented when his dad died when I was 11.

My mom has never been an attentive mother and devolved back into her old ways of drug abuse and unpleasantness. He was only 19 but stepped in and made sure that I was ok. He made sure she knew that if she laid a hand on me, he would keep her from getting her allotment of my stepdad's money.

He also paid for my college and was generally there for me. I had such an obsession with him that I didn't date until I was 19- I took his encouragement of this as a romantic hope. Which of course was ridiculous.

I know why I developed this feelings, but they drive me crazy. I have a good job and a sweet boyfriend who treats me well. But my heart skips when he calls. I buy new clothes to wear to our lunches. I constantly compare my boyfriend to him, unfairly. 

The worst is..he is interfering and controlling and thinks he knows best for my life. I should stop this. I'm sure I could. But I enjoy it. 

How do I live a normal life and move on from this implausible fixation on my stepbrother?

Could you distill the essence of the text into 1-3 sentences?
<bot>: I(22f) can't stop obsessing over my stepbrother (m30)-something that started when I was 7- even though I am in a healthy relationship and have a great job. Help?