Accidentally Forgot About My Beer...

It's fine... For many beers, conditioning beers (aging) is fine. I would say its good to go ahead and keg/bottle at this point.

 

Your beer should be OK. Now is the time to package (bottle) that beer.

As the Nike slogan states: Just do it!

Cheers!

 

As long as you used proper sanitation and brewing techniques when creating your beer, that length of time in the primary fermentor should not be in issue. However, I will ask if you know what the temperature was in that closet? That could be an unknown variable that might work against you if it was too warm in there. Go ahead and bottle the beer and you'll find out in a few weeks if off-flavors are present from fermenting too warm.

Just to get you up to date on terminology, that "dark, foamy stuff" in your carboy's headspace is called krausen.

 

Well, since @Mothergoose03 is providing some education here I suppose I will join in.

While this batch at 5 weeks could be OK, IMO it is not a best practice to permit beer to sit on the yeast cake for that length of time. I typically package my homebrewed beers after 1-3 weeks of primary fermentation since I do not want my beer to sit on the yeast too long.

@Peter_Wolfe posted on the topic of yeast autolysis in a past thread:

“You'll start seeing low level autolysis after about 3 weeks, IF 1) you started with healthy yeast, and 2) the fermentation temp was kept low (68F or under the whole time). If you start with unhealthy yeast or heat stress it, it'll happen sooner. It takes 6-8 weeks to start seeing wholesale autolysis that gives off the soy sauce flavor if you never transfer off of primary. In a big dark beers (especially stouts), this flavor is pretty effectively masked until it gets really bad, but it shows up like crazy in pale ales.

As they autolyze, the yeast release enzymes, lipids, and metal cations that all have a negative effect on flavor. Best way to forestall this if you know it's gonna be a while until you get to it is to cold crash it. The yeast will not autolyze for a very long time if you cool it down to 34-36 (cool fridge temps). You could have your parents throw the carboy in a fridge if they have room and you'll have some peace of mind.”

https://www.beeradvocate.com/commun...-too-long-in-the-primary.283588/#post-3572265

Cheers!

 

Beer will be alright, good advice above.

 

As long as the airlock was still wet, you should be fine. Probably not optimal, especially for a novice brewer, but it shouldn't be anything too bad.
Taste it as you rack to bottling bucket, if there are any severe off-flavors then dump, if it tastes OK go ahead.

 

Not disputing any of the advice given above, but many homebrewers regularly leave their beers in primary this long...and even throw the next batch on the trub to brew for several more weeks...and report no problems. What is technically optimal or sub-optimal isn't necessarily detectable in the product. Some interesting experiments along those lines at brulosophy exbeeriments. RDWHAHB.