Night of nights

So it finally happened. Lisa and I slept together. It took me completely by surprose and I'm not sure it was planned on her part either. It just hsppened. I will start from the biggining. One night in July we spoke of how we are friends and she desire was to not change that. My response was that whatever we do that would never change. Then I switched tactics and said why are we talking and not just making out. So we did. We started kissing in my livingroom and from there we went to the bedroom, but we never took our xlothes off. Not that I didn't try. She stopped things and I watched her leave thinking how close we came. Fast forward to three weeks later. We were outside at a concert in the village. We sipped wine and listened to music. I convinced her to dance and we were having fun like we always do. We called it a night before the end and as we walked back to the car I just spontainiously took her hand as we walked. I've done this before and usually feel funny about it and let it go after a moment or two. This time it just felt natural and we just casually did that all the way to the car. I did not think much of it at the time. We drove back to her house, which is only a block from mine. We had what I thought was a night cap and a little past 10 PM I started to look to call it a night. Before I could leave she said "come lay with me". So I just thought we would watch TV on the bed until she fell asleep. So I took off my shoes and follwoed Lisa into the bedroom. Ahe lays down and doesn't even turn on the TV. So I leaned in and we kissed. Then I realized at some point she had removed her bra. From there things are a little fuzzy. But we rolled around the bed and fell on the floor. We got naked. I touched her. Everywhere. She was hot. She was ready and willing. After 15 years of wanting this it was finally there for me. But my 50+ year old body was letting me down. I had nothing. Maybe it was the alcohol ot maybe I'm just old but I could not get an erection. And we tried everything. Her hand, my hand, her mouth. Nothing. We just fell asleep both not getting what we want. So we just talked in the dark. I told her how sorry I was. Somehow the subk=ject of how we'd gotten there came up. I told Lisa how unexpected this was for me. She asked my why did I held her hand earlier in the night. I said I hadn't even thought about it. If I'd known that was all it took.... but none of that matters now. We fell aseep together and when we woke up I got dressed and when home and fell asleep in my bed for about 2 hours. All I keep asking myself is will I ever be able to have sex again. I mean if I can't do it with Lisa how can it ever happen. I guess I can always see a doctor and get a prescription but things are so spontainious and that kind of thing needs to be planned. So in the last 2 weeks we have slipped back into our old routines. Lisa was away on a business trip only 3 days later and returned after the weekend. We have never talked about what happened and it feels like neither one of us wants to try again. Maybe that is best. Part of me feels like I've finally gotten it out of my system. I just hate to give up.