The first thing I noticed was you didn't say anything about love with Rick, not even "I don't know if I was in love with him". Yet, with Scott you do, that has to be the difference between then and now.
Another thing I thought of is not being able to say no, he ask and you say yes. Maybe didn't want to hurt his feelings, sounds far-fetched, but think about it, exactly how you were thinking, not feeling when he asked.
As well, even though 23 is still very young, you've had experience to know what you don't want, someone like Rick, Scott has to be the complete opposite.
I am no one to give advice, my last three marriages were "what have I got to lose?", meaning my life was so messed up, it didn't matter. But looking from the outside in, it's easy to give advice, or really just an opinion.
Just the fact you had enough sense to leave Rick tells you something, didn't stick around to try to 'change' him.
There's no garantees in life, but if you don't give Scott and yourself a chance, you'll never know, and always wonder 'how it might have been'.