What should i do i messed up really bad?

this is gonna be confusing to explain. Well my friend caught me flirting with their ex. My friend, her ex and all our other friends used to hang out at this place at school during lunch. After my friend broke up with her ex she stopped eating lunch with us. My friends ex started flirting with me i never thought about my friends emotions because they already broke up. Her ex flirts with me a lot in public. So one day me and my friends were eating lunch where we usual eats. My friends ex likes to flirt with me and women but, she tends to flirt with me a lot. So during lunch i was stretching my legs out and my friend got on my lap, grabbed my hands and smothered her breast in my face. One of our friends spotted out that my friends ex (the ex being my other friend.) don't no how long she was watching for but, she saw enough.