A few questions:
Is she sleeping well during the day? She's 8 months and should be getting at least one good nap during the day...like two hours or two one or two hour naps...then bedtime around 7 or 8pm. Now every child is different, but that is what I did with both my girls. If she's over tired from not napping during the day, she won't want to go to sleep at night and she will be restless.
What time are you starting bedtime? If it's too late, she's wound up and won't want to go to sleep. When they get over tired they just fight it after that.
Have you tried a warm bath before bed?
I know what you mean by crying when they cry. I was a wreck with my first. I trained her to need me from the beginning. She slept by the bed and I patted her bottom and stuck that pacifier in her mouth every time she grunted. As a result when I finally decided she need the crib..she couldn't sleep on her own. If she woke up, she couldn't lull herself back to sleep. I was a walking zombie.
At some point you have to realize that you need your sleep. This is what I did with mine at about nine months or so....when I finally couldn't take it anymore and was hallicinating from sleep deprivation.
I took her to her room, read her a story while I nursed her with a soft gentle voice...lights low. Then I put her down. I patted her bottom a minute or two and then I walked out. During the night when she woke up and started crying I went in, put her back down, patted her bottom a minute or two, told her it was night-night time, and walked out. I let her cry for 15 minutes then went back in and repeated the process.
The first night it took about four or five repeated trips to the room...I was exhausted. The second night maybe three trips. By the third and fourth night it was maybe two times. After a week she was sleeping six hours straight.
Do not pick her up. Lay her down, pat her bottom, shhhh her, maybe sing a short song. Talk quietly, keep lights low or off, don't pick her up. You give in and she will scream until she gets her way.
On one occassion my daughter screamed so long when I wasn't home (had gone back to work part time at night) that she threw up in her bed. She was hoarse all the next day. I cleaned her up when I got home, cleaned her bed, rocked her a minute and then put her back down. She never did it again. My hubby has a stronger constitution than I do.
At any rate, I had to train her to go to sleep after training her for months to need me. It was awful.
I didn't make that mistake with the second. She got nursed with the lights low, got her story while we nursed, maybe I would sing her a song and then she went in her crib....at three weeks old. She immediately fell asleep and has never been a real problem when it comes to bedtime. She's three now and after we do stories we lay her down. She sticks her little bottom in the air and most of the time I swear she's snoring before I get out of the room.