How can I simply and legally keep my exhusband's on again/off again girl friend from contacting me?

A simple solution is to block her number.

Yes, you may file a short respondive strict reply, only addressing what the other party alleges. No new facts or issues.

What Washington state court forms do I have to file to get my kids back asap

If you are on the birth certificate you Petition the Court for a residential schedule. If you are not you file to establish paternity and for a...

Is the alimony valid?

You may consider filing an amended petition to include that. I suggest seeking a consult with an attorney.

Do I need an attorney to modify the parenting plan?

Relocations are tricky. Is he the primary parent? Has he given you written notice? Have you objected? Yes, you should see an attorney.

Is swapping weekends with the other parent considered a major/minor modification in King County?

If there is no chance in the amount of time, meaning there are the same amount of overnights, then it us a minor modification. You may enter an...

Should I have to give my husband equity gain of my separate properties?

Many more facts are required before any advice can be given. The length of your marriage is critical. All property is before the court, separate...

Do I follow the paperwork/procedures for 'divorce without a child', or for 'divorce with a child'?

You would file without child as your marriage does not have one and child support and a parenting plan is not at issue.

Can she just take him like that? If we go back to court will the fact I've had him help me? Advice?

She is allowed because that is what the parenting plan allows but you might have a substantial change in circumstances to be able to move for a...

Can my mom get a small alimony from him after 20 years of marriage and taking care of him

Once they are divorced she cannot be covered on his health insurance but she might have a good argument for temporary spousal support.