You sound like a total sweetheart!
You loved someone, deeply. Though complicated, the love was real. No one just gets over it in a day.
You are taking the first tentative steps into a new life. It doesn't mean you have to go on a screaming tear. It feels a little out of control when you step outside your cocoon..
Harmless flirting can be lovely, and a sweet ego boost. It doesn't have to go any further. Your mind and body will guide you as to when you are ready for anything else - but you are under ZERO pressure. Have a smile and a laugh - you are ready for those things. Take in the good.
You sound like you deserve a lot of good. A summer at the ballpark with good friends sounds like a great recipe!