The lip seal on the rear of the pump has gone and it's sucking engine oil into the suspension oil.

You need to clean out the suspension by disconnecting the shocks from the spheres and pushing them up so the oil comes out ,replacing your failed spheres ( new hoses are good idea if engine oil has gotten in there. )
Remove the reservoir and wash it out and replace the filter and low pressure return line .
I find it better to disconnect the pipes for the suspension and blow air down the pipes to get the worst of the engine oil out.
Your rear valve has failed so repair that and replace the link rod too,the ball ends will be worn by now.
When you have the spheres,hoses and the pump back on the block,fill the reservoir with new SLS fluid (NOT hydraulic oil,auto trans fluid ,Citroen HS oil or brake fluid...) and bleed the high pressure line by aiming it from the pump into the reservoir until it runs clear.it takes a few seconds to do this but if you dont because it seems liker too much work,the pump will fail again.
Reconnect it to the pump and sit the car on it's rear wheels. Load the rear with 100kgs of weight ( I fill four 25 liter buckets with water) and with the engine idling and a hose connected to the rear valves bleed nipple,let the pump run oil through the valve until all air is ejected. The back should rise to it's full level and remain there once the valve is tightened up. Check for leaks etc.
The lower ball joints on the rear hydro shocks can wear out so if the shocks are oily and you hear clunking sounds from the rear,the shocks need replacing. Same story,load the rear up and bleed the suspension .
The oil from the bleed process can be used again,just stick it back in your reservoir.
In future,anytime the fluid looks dirty,it's a clear sign you have a problem that needs attention. It should remain clear all the time.