Its been too long now...

Okay so, I'm 21 and in the 18months since i split up with my ex girlfriend I've had 5 sexual encounters, none of which have started or ended how we'd all hope.
For that reason I've actively avoided more encounters due to sheer embarassment on my part, and feeling sorry for the girls I've subjected to this.

My self diagnosis without waiting the ridiculous amount of time to see a councellor is depression. In a nutshell I had to turn my back on a girl who was so upset she collapsed in tears and fainted. I considered myself a very empathatic person but I wasn't going to give in and give her a 5th chance. To follow through with this I had to rip what heart I had out of my chest, and it feels like its gone for good.

I now feel no extremes of emotion as i remember them, no motivation to succeed, drive or ambition. I've sat through conversations with people pouring their heart out to me and not felt a thing. I wish i could say this makes me feel sick, but I'm just void.

Since the break up I've used porn to masturbate, which I get the feeling is counterproductive. I still get erections maybe two mornings a week, and when im say kissing a girl I still get one too. When it gets to the nitty gritty things go downhill.

The first limp encounter was admittedly a crazy drunken mess, but I was pulled into an alley by a girl Id only met in a nightclub and It took me a long time to get an erection.

Since that instance, every time Im in a situation where I could have sex, i think of the embarassment if that happened again... which inevitably makes me anxious and I get the same problem, adding to that anxiety every time.

NOW... the big question is, how can I forget about the anxiety which has built up over the last 5 sexual encounters and 18months of constantly thinking about it? Ive pushed girls away who i considered great friends beforehand and Its gone far enough. so can I just get on with it without worrying so much that it wont happen?

Any help would be appreciated more than you could imagine.
Thanks, Dave