I suggest that you move, since no solution will make you or your neighbor happy.

Have you asked her, recently, if you could have the trees removed? She may be more amenable to that now.

I strongly suggest that you talk to a lawyer regarding your rights. Seems like a letter from an attorney might be helpful.

I would also consider talking to an arborist about what can be done and how it might put the trees at risk so that you know what is possible.

Yes, an arborist is a good idea. Where I live, a neighbor whose landscaping grows into my lot is not obligated to pay anything if I have it trimmed. And you are right in that if I get something trimmed, and it damages the tree/plant, then I can be liable. See what an arborist suggests.

However, if you want her cooperation, when dealing with her, you'll catch more flies with honey than with vinegar :)

In your community, do they have constables or justices of the peace who mediate some of these things? That might be an option for the 2 families and one of those mediators to see what can be agreed upon. Perhaps these folks have some legal authority and can get said agreement in writing.

Taking into consideration that she is kind of admitting to the problem, but is also saying she is on a fixed income, which I can understand.....if you don't have money, then you just don't have it......would it be possible to talk to her about splitting the cost of removing the trees. I realize you didn't plant them, but since they are a problem for you and you have also considered paying someone with a bucket truck to trim them, seems to me you wouldn't mind sharing in the cost of removal. I would at least try to talk to her about doing it that way as it seems there isn't much other choice.

I would also think that if you had them trimmed, they would look as funny from your side as they would hers.

I have always hated Leyland cypresses. I cannot tolerate that "wall-o'-green" effect that seems to be all the rage in subdivisions throughout the Southeast. Leyland cypresses are as much an abomination as Pampas grass. What horrors they both are. As far as Leyland cypresses are concerned, there may be a glimmer of hope on the horizon, at least in this corner or Zone 7B. I've noticed that many Leyland cypresses seem to be succumbing to some kind of disease. Many of their branches are beginning to turn brown. One can only hope that whatever is killing random branches will soon kill the whole plant, thus ridding our landscape of the horrid "wall-o'-green."

If the neighbor claims she never considered how tall the Leylands would get you need to get that in writing before you proceed.
Then, get creative! Make lemonade out of these lemons!

Since they are on her side, explain what she has is a great opportunity to use these living fenceposts and only have to span between them.
Get an estimate for her showing the cost of having the trees topped first leaving a 6' trunk and trimming off all the remaining branches.
Then give her some ideas to span between the trunks a privacy fence and get creative.
Simple coated wire between trunks every 6 inches up the trunk will support plantings of carolina jessamine or bignonia for a living fence. The jessamine is evergreen while the bignonia is not so much (depending where you live) and depending upon how much sun hits the side yards.
Obviously, the simple wire spans are the cheapest solution to retain a fence she wouldn't have to maintain.
Since you acknowledge the trees were planted on her side of the the property line it is up to you if you want to contribute to the cost of having these trees trimmed/topped.
It would probably serve your best interests to assist her in the costs.

Tell her that since these enormous trees are not what she had in mind 10 years ago this might be a solution you can both live with and improve the property value for each of your homes.

Finally...success! Her spite fence of Lelands has been removed! We basically told her that after years of this problem, we were going to either have them cut straight up along our property line, leaving very bizarre half-trees that she would have to trim on her side OR we would have them removed entirely (with her consent). She agreed to the latter and we paid to have them cut down, which turned out to be not much more expensive than the trimming would have cost.

She has since done some landscaping where they used to be, and everyone is happy with the solution. While I could wince a bit about having to pay to solve a problem caused by the neighbor (as she drives around in a luxury car and seems to have no problem hiring people to do landscaping projects), it was ultimately worth it. The result looks much better and we have one less thing to argue with this lady about...

You could have given them a good trimming and not hurt them. I see the power company in my area chop into lelands all the time and it doesn't appear to hurt them one bit.

Did they remove the stumps too?

It seems a trifle odd for any gardener to be gleeful about a disease wiping out a species of plant. Some people may love their Leylands. I have seen some very pretty ones and find it sad to see them decline. It is not the tree's fault that they were misplanted and mistreated. That is our shame.

Glad there was a happy ending, I was going to suggest telling her if her trees did damage to your house, she is liable. That's the way it works here anyway.
I have seen them used as a very nice break and I have seen them planted in places that just make me wonder.

i have this neightbour from hell access order has been granted monday neightbour to pay costs £ 55 . for scaffolding to go up to reduced chimmney stacks 60 feet up very dangerous state now their have planted tree stump from top of the leylands but no root at moment so a gentle pull will bring it out no soil no roots my house is six feet away she is doing her very best to totally make my life a complete hell on earth .wants rid of me and my family but i am old 1932 detached house so me going no where she will end up with injunction or maybe . ahefty legal bill 219 police incidences.