Need Friendship Advice, Please!

I posted this on my other support group site, but I need all the advice I can get, so I'm posting this here as well. I hope I don't offend anyone who is a member of both sites with a repeat post.

I'm hoping to that some of you can relate to this, as my husband and closest friend just don't get it because they're not bipolar.

I have this friend that I've known for 13 years. She has been one of my closest friends through most of that time. She has BPD- Borderline Personality Disorder, so she puts on facades that aren't really her to fit in with the people around her. If I say that I don't like something she's doing, she'll change it to keep me as a friend, even if it isn't true to her personality, and eventually will relapse back into the harmful behavior.

Lately she's been engaging in destructive behavior. Last night she posted on craigslist looking for a one night stand even though she has contracted STDs from her promiscuous behavior. She won't take her medication regularly, but then complains about being depressed and unstable. She wanted to go back to school, but blew the money for it on junk for her house. She started compulsively lying again.

I have been with her before, supporting her through her rough patches, but this time I don't know if I have it in me to help pick up the pieces when she eventually wakes up and realizes the mess she's made of her life. She won't listen to me, and I've accepted the fact that I can't change her, she has to want to change herself first. I had to end our relationship before when she refused to take care of herself, but we repaired our friendship after a year of not talking. This has her scared that I will leave her again. She has almost no real friends besides me.

This is the part my family does not get, and I'm hoping some of you might. My husband and closest friend believes that she is not good for me, as she is not a very good person at heart (she lies, used to shoplift, is not very compassionate, is self-centered, inconsiderate, and is often rude)
However, despite all her many flaws, she loves me and has been extremely supportive as I struggle with bipolar disorder. I need all the support I can get some days, and I don't know what I would do without her. We've been through a lot together, and I view her as a sister, although a dysfunctional one. I don't want to stop being her friend, but I can't keep exposing myself to her negativity and rude comments (she occasionally says comments that demean me and can be overly critical, partially due to her mental issues- she has no tact), and I can't witness another roller-coaster of self-destructive behavior.

I'm extremely shy and I do not make friends easily. I depend on my friends and family to help me through the rough patches of this disorder, and if I stop talking to her until she straightens herself out, I will be missing a large chunk of my support. But is it healthy support?

My closest friend suggested I give her an ultimatum- "straighten up or I can't be around you anymore." I know if I presented her with that, she'd put on a facade to comply, but in reality she won't change because she doesn't want to. I can't help her, she has to help herself.

I guess I said all that to ask this: Should I continue a friendship with her? Is this a toxic relationship that is actually harming me? Any advice for dealing with this mess?
Thanks for listening/reading this long post. I'm done now.

This is a really tough question to answer. I guess I would make a list of the pros and cons of keeping her as a friend and see if it makes the solution easier to see.

I agree with wing'it. This is really a tough question to answer. Just do what your gut tells you to do.

If she is your friend you should be able to actually talk to her, be honest tell her how much you value the friendship, tell her what it's doing to you, she may just see that your wanting her to get some help is coming from a place of love, wouldn't you want the same treatment if you were doing those things? You can't make her...but you can express your concern, in the end you really do have to look after yourself first if it is causing you pain i would say stop doing it just like if you were sticking your finger in a light socket..i would tell you stop doing it...whether or not you choose to is up to you but sometimes you got to let people do things and wash your hands of it because there isn't anything you can do. Maybe you will get lucky and after a talk she will make real changes and you guys can continue with the friendship but not talking about it never allows for that to happen...so take a chance imo..best of luck with whatever you decide

Really good advice from everyone above.
Yes, I can very much relate. Too much. Though details are different, the dynamic is very much the same. Much empathy for your turmoil. And turmoil it is, yes? Trying to weigh things of such disparate natures...

You do need supportive friends but is she being supportive to you?

Thank you all for your comments and support. After really taking an objective view on the relationship, I realized that she is getting really sick. She made some inappropriate comments about my baby girl, who is three going on four, that make me think she has pedophilia urges and no matter how supportive she has been for me, I absolutely CANNOT risk my daughter. I was in denial about the severity of this situation, but writing about it and really looking at the red flags that have been staring me in the face means I can't stand idly by anymore.

This is what boundaries are for, if you decide you want to keep some part of the friendship for some reason. But you don't have to entrust and hand your whole life over to her on a silver platter. It's not a poker game where you're in or out (even if my mother treated our r/s like one, and only one winner). As for the remarks about your daughter, these may be coming from her own unresolved CSA issues, not actual intentions or leanings.

Though I may certainly be the wrong person to go to for friendship advice, I'll attempt to stifle my inconsideration, as you certainly seem to be doing bad enough as it is. In my humble opinion, she definitely needs to be left on the wayside. She's not a good friend for you, let alone anyone else, & perhaps if left alone long enough; she'll realize why. Just because someone is/was your friend does not mean you should have to hold yourself back just because they choose not to better themselves. I hope you're going to do well after this, as I can imagine losing a friend is a rough experience, but it's wholly necessary for both you & her. She can't continue to be enabled by the charade she puts up for everyone & for herself. If anything, you saving yourself is the best thing you could do in the situation. Especially if you feel your child is at stake.