I don't think as an adult a friend can abuse you. You can talk back and walk away, etc. They certainly can try to abuse you, say ugly things but pushing triggers that are already there I don't think constitutes abuse. I think friends can betray you and hurt you but if they hit you or say ugly things then they're not friends. But abuse is a power thing; friends are "equal" to you so don't have any power. A spouse can have power or a parent, therapist/doctor, etc. but there's nothing to "hold" you to a friend in a forceful way so they can get in a position to have power over you, you don't have to "stay" like you might in a family situation where you're physically and emotionally dependent on someone. Any "power" a friend has is 100% given by you so can be taken away by your will alone.

It's hard though when you love and trust a friend well and they hurt you or tell your secrets, etc. We do "invest" some of ourselves in friends so having to decide to leave and/or dealing with their behavior that has hurt us can be difficult. All intimate relationships are very complex and untangling can take a lot of work and I don't think it's "weak" to take time getting untangled/figuring it all out and what to do about it. But it's very much an individual thing.

I think some "abuse" is very clearcut but I also think we all have "soft spots"/triggers but just because we get hurt there, the other person isn't always responsible for that hurt, may not even know we have a problem there that they should treat "gently." An alcoholic might think it's "abuse" if they buy liquor and a friend pours it down the drain; it's certainly a boundary violation. Drunks who have friends confiscate their car keys can get really angry. Lots of family members have fights and cease speaking to one another for one thing or another. But anger and hurt are not always the result of "abuse."

If I thought I were being abused by a friend though, I'd have a hard time figuring out why I wanted to stay with that "friend"? Unless I were sharing an apartment and needed time to get money together or a job, etc. I can't see why I'd stick with them. Or, if I did stick with them, I'd reframe the "abuse" in some way.

My husband once smacked me hard and it took all my willpower to not kill him on the spot :-) thanks to my stepmother's abuse growing up, but I have enormous willpower so was able to stop and ask him "why" he'd hit me. He explained how I had almost seriously injured us both. He was right and I'm very honest so could let go of my anger and apologize for doing something stupid causing him to have to hit me. I'm keeping him as a good friend.