The leaves of sanseviera are very stiff I would check the health of the roots or accuire more help in The sans forum

Here is a link that might be useful: Sanseviera Forum

Sansevieria is well able to hold itself up, very tall, but I suspect the roots have been kept too moist, which has caused them to rot, which is why the plant can't stand.

If it was my plant, I would take it out of the soil and let the roots dry for a few days, discard the old soil somewhere outside, then put in a pot of fresh potting mix that drains instantly and dries quickly, within a week. If that pot has an attached drain saucer, like the "self-watering pot" next to it or of another type, I would remove it when watering, then put the plant back on it when finished dripping. It should snap off, then the pot can just rest on it, instead of being attached. That way you know you're never killing your plant with standing water. Until the soil in the pot is dry, this plant doesn't need a drink.

When it leaned over, if it was leaning toward the light, it may prefer having more light although they're not that picky if you like it where it is. The less light, the less quickly it will use water. You can also rotate the plant halfway once or twice a month to keep that from happening.

With the leaning issue you have, you might find some rocks helpful in holding your plant upright in the new soil, until it's recovered and grown some new roots because you wouldn't want to submerge it more than it currently is. At that point, when it's holding itself up, you should be able to know which leaves should go (any that aren't upright, IMO,) but I wouldn't do it until the plant recovered its' health. Those weakened leaves are unlikely to propagate but may be able to help the overall plant recover more quickly by staying attached.

Is that a bromeliad in the self-watering pot? It is probably becoming unhappy also if it's staying soggy also.

Good advise given. Also take out of pot and let the roots dry off and repot in smaller pot with cactus mix with perlite and coarse sand. Don't water untill a few days and then only a little. Also tie up those leaves. I used a tomato cage to hold mine up right untill they recovered. Can you give it more light? Keep out of direct sun for now.
Good luck.
Stush

Did you repot after you bought it? Or is it still in the same pot?

I have never seen or heard of this. I agree with purple and stoosh

I think I read somewhere once that if watered too much int the winter, Sans will flop over like that.

Planto