We cant send a letter for you as this service is for online information only.
In relation to the matrimonial finances - as you have not remarried you are still able to make a claim in relation to the same. You do need to consider doing this. Whilst there is not enough equity in the house for it to be sold and your ex and the children to be rehoused, a court will make an order as to what your share is and when you will receive this - this will likely be when the youngest child reaches 18 years old. It may also be the case that the considers that because your ex has remarried and his income is higher than yours he has the ability to buy you out now. The starting point is an equal division of the equity.
You can also claim spousal maintenance because your income is a lot lower. There is no set rule but the court will want to make sure that you have enough to meet your needs.
To do this you first need to refer to family mediation. There are lots of family mediation services and there will be one local to you. Google family mediation in your area and give them a call to self refer.
You can still get legal aid for mediation and they will undertake a legal aid assessment with you.
If agreement can be reached in relation to your share of the property and spousal maintenance at mediation then you need to have this submitted to court as a consent order. This will make it legally binding for you so you can enforce this if you ex doesn't comply in the future.
In relation to the children - you need to know that it is the position of the courts that children are entitled to a really good relationship with both of their parents and this should prevail as long as there are no child protections concerns as to why this cannot happen. The reasons your ex has given you are not of a child protection nature and he needs to be promoting your relationship with the children.
Mediation can help you in relation to the children also. They will try and help you agree a routine without the need for court but if your ex wont agree then they will sign the form tat you need to apply to court. This is the same for the finances.
I know that you have said you are trying to avoid court but in your circumstances given that there is no agreement in relation to your financial settlement yet and you are struggling financially and also given that you have been denied a relationship with your children for so long you really do need to do this.
I note how your ex has previously treated you. Given this behaviour you might be able to get legal aid and have a solicitor help you with both the children matters and the financial matters. You first need evidence of domestic violence. Print off this letter in this link and take it to your GP. Explain how your husband has previously treated you and how he is still treating you such as denying you a relationship with your children. Ask your GP to refer to you to a domestic violence service so that you can get support for yourself and then take the letter to your local family legal aid solicitor so that they can assess your means. Given your limited income and the limited equity in the house you should be able to get legal aid for both matters.
The solicitor will then be able to write to your ex with proposals in relation to both the children and finances and if agreement still cannot be reached then they will be able to issue court proceedings for you and represent you at court.
Its better to do this now rather than waiting as the longer you don't see your children the harder this will be. You need to rebuild the relationships asap. If your ex says the children dont want to see you then a court officer (cafcass) can be asked to speak to the children and ascertain their true and wishes and feelings and also see if they are being coerced by him. The court will work from the premise that your children should see you and he should be promoting that.
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