Inititating lawsuit in Belgium from abroad (Brussels)

Hello everyone!

I am not really living in Belgium, however, my ex-wife is, and appears we are getting deeper and deeper into problems, which I am failing to resolve.
We have common daughter, and that is where all the problems are coming from.
We have been divorced for a bit more than 3 years with a mutual agreement stating monthly amounts (child maintenance costs + what I committed to deposit to savings account for the daughter) and my rights to see daugther. A big failure of the agreement - it does not state any details how do we establish and ensure my and daughter rights to see each other, only that I have the right to see daughter not less often than every 3 weeks and during school holidays, thus it is all me taking care for that (arrangement and costs).

The relationship since our divorce was never a fairy tale, but now, when I finally started to believe I deserve a little bit more from life than just going around, swinging with the credit card and paying left and right for every additional thing my ex forwards to me, and got a girlfriend after 3 years living like a monk - it is all going to hell completely.

She is not only demanding me to pay double to what we agreed, she also threatens - if not, she is taking me to court.
Well, I am 99% positive she is bluffing about the court, because she is guaranteed to lose it (I have my facts ready why so) and, hopefully, she is well aware of it.

I fail to find a common language with her - tried explaining there is only as much money as there is, and I cannot fulfill her demands even if I tried. She couldn't care less...

This is simply killing me - ex is just demanding, if I don't obey, she turns the "daughter's card" and this is where I have been giving up so far, because I do care for my daughter.
It is getting worse and worse with each day, if it started from our agreement, daughter having her tablet and phone and us seeing each other on a frequent basis (which was a few weeks, sometimes more, sometimes less), then now daughter is not allowed to use anything (I am forced to call ex's number at a specific time in the evening and even then I have no promise we will talk) and arranging travelling has become a full scale battle every time. At the same time - ex keeps doing whatever she wants and then forwarding me the costs to cover.

The tendency is obvious and that is something which I want to stop. I have tried to find a common understanding and a new agreement which would make sense several times with no success. Everyone around me is saying - Kaspars, stop being an idiot and let a judge do his/her work. Let the judge decide - how much you have to pay, how much mother does, how do you communicate with your daughter, who pays for what, who reports on what, how often and so on and so on...
And appears, I have to give up trying indeed, so, whew!, after such a long prelude I am finally getting to the point.

I have been googling around, trying to understand how do I exactly start a lawsuit, and I have to say there is no direct answers:
1. What court should it be? Can I submit it my country and it will forward it to Belgium or...?
2. How to submit lawsuit - can it be simply mailed or I have to do it in person?
3. In what language can I submit it? I don't speak neither French, Flemmish nor Dutch or German. Can I do it in my own language considering it is official language of EU Member State?
4. Do I need a lawyer for that? In my country lawyer is optional in civil cases, while in the country where my ex was residing prior to moving to Belgium (yes, if I count the time when we were still married, then in 4 years she has moved to different EU country...uhmm...4 times now already, without asking my opinion at all, just - poof, here I am, suck it up) it was mandatory - i.e., only lawyer can submit the case to the court.
5. What are the costs? Those are a big problem to me, considering after paying up for everything the ex makes me to and just common bills and expenses I usually have nothing left.

Hope you can answer at least some of my questions, or direct me to some agency or someone who could answer those...

Thank you, really looking for an answer,

Kaspars