Windproof jacket for winter riding where I live winters usually are -15°C to 5°C. For MTB I wear sports base layer and fleece jacket, but problem is wind goes right through making stomach and chest area very red and painful. I have a cheap windproof jacket, but it's unbreathing and sweat condensates on the inside, so stopping even for a short time in those temperatures while wet is dangerous for health. Wearing base layer + fleece + backpack i don't feel cold at all. All I need is something windproof in the front and still very breathable. 
Would cycling gilet/vest/waistcoat be sufficient? Are their fabric windproof? Maybe long sleeve windproof jacket is better, but are they breathable? Or maybe loose fleece at all and go with something else like softshell jacket? Please share your experience.
Specific product recommendations are off topic on this site as they tend to become obsolete quickly.

There are plenty of breathable windproof, cycling specific jackets available and reviews are easy to look up.

Wearing a wind-permeable fleece on a bicycle in cold weather is less than optimum because cycling always involves wind (although you are moving relative to the air, rather than the wind moving relative to you. 

When you add a wind-proof layer to your fleece you are probably over-insulated and get sweaty when riding, then cold when stopped. Try a thinner insulating layer, and open zips etc to get some ventilation when working hard and avoid over-heating.