Hi Peggy
To be blunt, you both sound as bad as each other. Your ex certainly should be paying you child maintenance (or perhaps the mortgage in lieu). On the other hand, what you are saying does sound a bit unfair too with regards to the move & the house.
Firstly, you argue that DD needs continuity but at the same time you say you want to move 200 miles away. How is that continuity?
Secondly you expect your ex to not sell the house in case you come back? Well that sounds unfair in so far as it's open ended. How long does he have to wait? 1 month? 6 months? A year? It might be better to say for example "Let's delay selling the house for 3 months until we're sure DD is settled" I've found its always better to have specific targets.
You also say you would never stop him from seeing his daughter but those words must sound hollow to him. Physically moving 200 miles away practically stops midweek contact. How can he maintain every other weekend & 2 nights in the week when a distance of 400 miles is involved? Where will he stay if he has to come to you? And your DD will have to endure 400 miles every other weekend of travelling if its the other way around. Trust me, four years ago, I moved 100 miles away and my kids have done the motorway run for the last 4 years. It's far from easy and although we're happy & settled, if I had to do it again, I would not. The impact on their relationship with their mum has also been great.
The whole introducing your DD to a new partner thing usually also boils down to one thing. Your own insecurities. I've yet to see a child totally confused as to who their parents are because they were introduced to a new GF/BF. Over the years my kids have seen a few people come & go on my side & my ex's. Yet they remain emotionally stable. It's only a big deal if you make it a big deal.
Sorry if you think I am being harsh. I do get it. Much of what you say resonates with me as I have been in similar situation. In times of uncertainty we want to go home. For you that is down south, near your family. But all that glitters is not gold. A while back I went through the same. I yearned to go home. I was even willing to put the kids through another upheaval.
Eventually I looked at things logically rather than emotionally and realised that once the dust had settled, I'd probably be financially worse off than I was now and our lifestyle worse.
My advice would be to think very carefully.
Oh and lastly just to add, with a contact pattern like your ex currently has, if he took the matter to court to stop you moving. With a good solicitor, he'd have a fair chance of a shared residence order