Here's a problem...

Soooooo, i seem to have gotten myself into some kind of predicament here, one that can lead you to a dangerous situation if you don't pay attention, but let me explain:

I've just found out, a couple of months ago, that i have a major issue when it comes to relationships of pretty much any kind: i have this instinctive defense mechanism that pushes people away the second i get the feeling they might get to know me too well because i fear that they might abandon me if they found out who i really am. It's been going on for quite a while and has been the roots of me changing my circle of friends pretty much every two years, not to mention my girlfriends with whom i break up all of a sudden, using their quirks as a reason.

The thing is that i don't trust people not to abandon me, so i tend to use this kind of "no feelings, no shame" façade whenever i feel threatened.

As i said, this has been going on for quite some time (8 years in fact) and i've only just found out about it with the help of this girl called Mag that managed to see through the bullshit and stand by me without making me feel threatened.

We've basically made an agreement: we live together, we share the same bed, we sleep together, kiss, hug and all the other stuff people do in relationships, but we're not together. No promises kinda thing.

And it seems to work too, i don't feel threatened by the fact that i'm missing out on other opportunities or that she migh break up one day, and we've been happily living together for about 6 months.

The problem is that a couple of weeks ago i ran into my ex, we had been together for about 3 years just before i met Mag, and the break up didn't go so well (read my previous rant if you want the whole story).

Well, this led to that and we ended up sleeping together again. And again, and again, and now we're pretty much seeing each other every week at her place.

The thing is that i know that Mag is cool with it, like i said, no promises, but i can't help feeling bad about it, like i'm cheating on her. And i know it's never a good thing to go back to your exes just for sex, but i can't help it, it's like i get this fear of missing out on something that i should be allowed to have...

Anyways, what can i do? Any thoughts?