Ex wants to get back, im not sure i do

Im genuinely looking for advice here. I was with a lady for almost 10 years and we broke up in 2014. We have an 11YO daughter and remained close friends throughout our 5 years apart (spoke regularly, helped each other out, became genuine friends even closer than we were when together)

During the period apart I had 3 relationships including one very difficult one which ended about a year ago. That Ex was mentally abusive, and prone to starting arguments and throwing insults that were deeply hurtful.

Coming out of this bad period, my long term ex began spending more and more time with me, she having herself broken up with her BF recently at the time. She floated the idea of us trying again and i jumped at the opportunity. I realize now it was a mistake to make the decision when i was still in pain, but that said i still would have attempted it. I have always been close to her and we regularly hung out as friends. So naturally i think it was worth looking at, and occasionally i even wondered whether we would try again. We are that close, and this despite her family hating me

The trouble is that nearly a year on, having spent quite a bit of time together, i am just not feeling it.

In terms of sexual chemistry, it seems to have vanished for me. LITERALLY, i feel almost uncomfortable when she makes a move. I have never had that with anyone before, and while i dont sleep around, im as red blooded a male as its possible to be. But with her, folks, i dont know how to put this. It just feels wrong, entirely. And just to be clear this lady is incredibly good looking. She is a year older than me at 39, but could be IDed at a bar depending on what she dresses up in.

In terms of spending time with her it is becoming something i attempt to avoid. Case and point, i just told a bare faced lie today; She is off work for a week from thursday, and grandparents want to take care of our daughter. Im working at home as an accountant ATM RE the pandemic. So she planned to come and stay for a week. And i felt i had to pretend i am under the weather and not up for company (barely keeping up with paper work, tired, bit stressed, which is a white lie as i am actually under pressure atm)

Although we agreed to give it a shot, in the early days about a year ago we both agreed not to rush things. We would date, and see what happened. And make nothing official. I feel i have stuck to this plan, but she really has roped me into it. Most of her friends think we are together. Her family and now my family. She is now talking mortgage, kids, marriage - and this puts me in an aweful position. I dont want to hurt her, and in truth i dont know where it went wrong. OR if it has in fact gone wrong. Maybe im reading too much into things.

Iv spoken to her about the fact that i dont feel what i expected to feel spending time with her. She seems the complete opposite and tells me she loves me intensely and that things will be great once we commit to one another.

FYI i should also point out that the lady in question has a history of depression and anxiety, which further complicates things. I am concerned for her well being.

I dont know whether to keep trying or make a firm decision. It feels like if i decide to call a halt it will be like breaking up with her all over again, because despite our agreement to be slow, she has clearly assumed we are an item

FYI ALSO, no other dating is involved on either side, just so that you folks know that there is no third party waiting in the wings

Advice in relation to this would be great. Also if there is anyone who has experience getting back to an ex after a long time. FYI i mention the sexual aspect not to be crass, but to contrast the situation to previous relationships i have had. I have gone from being a regular loving man, genuinely desiring a healthy exciting sex life, to a guy who makes any and all excuses to avoid it (im tired, i dont feel well, not in the mood, too stressed, not feeling it etc)