My advice is to do a really easy but effective step in seduction that is the next time you see him, to do some acting and pretend like you're so over him so literally treat him like an old friend. Smile, ask how how he is, fill your face and your emotions with happiness, he's just an old friend. But then cut it short and go about doing what you were doing because he's an old friend but you don't have time to talk to him because you have other stuff going on you know, new stuff. No one wants to feel like someone has gotten over them, even if it's someone they left. It's just a kick to the ego and your emotions to see someone who once paid you so much attention, not pay you that kind of attention anymore. Then I would actually avoid that scene for a period of about a month. It's no contact. Instead of going to those gigs, start just going to house parties or try going to other kinds of gigs. I'm part of a rave scene in my city, I had a similar problem but then I just decided to go to other places if I knew where my ex would be. Two reasons: A. Because when you're not around him, it forces you to not have your mind entirely on him and gradually over time, you start to get happy going out again and talking to new people and making new contacts and B. It gives you mystery, it makes people wonder what you're up to when you're not around. 
If you can do this for a month, you'll also give yourself a good time to heal and meet new guys. Just because you've chosen what you want for dinner, doesn't mean you can't look at the menu you know ;) By chatting to other guys, you'll get more confident in yourself and also be open to going out with them on dates, you could discover new things like foods and perspectives. 
Then after about a month, you could go to a gig where you know you're person will be and where you'd like to be too. Only go if you feel emotionally ready and confident and attractive in yourself. Wouldn't even hurt to bring a date or a guy 'friend' you know, that would give you a confidence boost and an extra reason to feel sexy. 
No matter what, that girl will always be afraid of you because you were there before her. She will make life harder for you even if it's subconscious. So she'll kiss him more, be more affectionate to him, get his attention more...and that will be hard for you to just ignore ! The only thing you need to try and do is keep your mind focused on the bigger picture and keep a mantra 'this too shall pass' and feel confident in your worth. If you feel that bang of emotion, just turn away and look at your friend or date. Or maybe even leave subtly. Not being around him so much is good actually. You don't want to look like a clingy ex or a girl who doesn't change much or move on. A break up happened, first thing people do is take space from each other to get over each other. It's understandable for you to take space if you haven't already, it doesn't make you look weak or threatened, it makes you look like you're moving on and doing new and exciting things. 
If your next interaction with him is one where you can really convey that you're A. Moving on B. Happy and excited about the stuff going on in your life and C. That you're cool with him but not overly excited about him or anything...he's like an old friend and that's it...then you can successfully grab his attention subconciously and if you then disappear for a month from his world and then come back looking and feeling much better than before, then you will be on the way to attracting him back
She's irrelevant except that she's an obstacle that you're not getting over right now. She's an ice berg and you're trying to cut right through her when you really need to be going around her. Which means not being near her for a while until you're really ready to not only be near her, but out-shine her  

Just keep the focus on the end result of your goal and not on the minor things like every interaction or every gig or ever practice. Don't worry about that stuff, it'll be perfect when you get some space and get happy