Let's say you and your girlfriend are dating. Suddenly, she asked you if you love her, then you immediately blushed.
Girlfriend: Do you love me?
You: (blushing) Of course I do, I won't be blushing if I dont. (1st conditional)
Or
Girlfriend: Do you love me?
You: (blushing) Of course I do, I wouldn't be blushing if I didn't. (2nd conditional)
When using conditionals, it depends on the context of what you are trying to say, moreover, sentence1 & sentence2 in this situation that I have given is what I am not sure which one to use. Conditionals are usually hypothetical, but here, it is still happening.