I came out to my sister-in-law last night. The plan was only to tell her that I'm into men, and see how she would take it. If it was a positive response and she didn't tell a bunch of people, I'd come out about being trans. Things don't always go to plan..

For the record: everything was face to face, and the opening line was: "When you have a chance, I'd like to talk to you about something and I don't want to be interrupted by anything while we talk about it"

I picked her because she has told me she loves hanging out with gay guys in the past. Her response, while VERY shocked, was extremely positive and supportive of it. She even went as far as saying, "If you want I'll go to gay clubs with you. I love going to them. Your brother used to get so mad when I'd drag him into them." When I asked her why she likes going to gay clubs, she said, "They're fun, the guys there are just a blast and I love watching the drag queens.", which gave me alot of confidence actually.

During alot of conversation I hinted that being into men was really nothing compared to a bigger secret. She told me to just tell her, and that she would love me and be there for me no matter what. I told her that I was transsexual, and she didn't know what that was. After explaining it to her, she was supportive. She even apologized for the whole thing she said about drag queens, but I told her that's what gave me alot of confidence to tell her the whole thing.

While being supportive, she said a few things that made me think she's not as supportive as me being simply gay.

Saying things like:

"I might not agree with you on it, but I'll always be here for you, and I'll even take you to get surgeries if you want me to."
"All of this doesn't change who you are on the inside, you'll always be who you are there" (Although she may have been referring to my kind nature other than any change in my gender expression)
I told her that I would love having a girl helping me with things that are girly, she had no response to that..
(On having male clothes)
"I'll go shopping with you to pick out clothes, you need them."
"Yeah but then I'll transition and wont need them anymore.."
"Well until that time comes I'll go with you to pick out clothes.."

Overall, I think it was extremely positive. She even shut out her 4 screaming kids to make sure we had a nice long talk about everything. We then watched a couple of movies. Well, I watched 1 while she played on her laptop next to me and she watched most of the second one with me. This lasted until 3:30am last night and I finally left. I told her I may come over today to hang out, and she said, "You're always welcome, like always.. just call first to make sure I'm home. We'll (her and her kids) will just be twiddling our thumbs, alone,  doing nothing tomorrow anyways."

I want to hang out with her, but I'm not sure if I should just give her a chance to absorb it all. If I had to guess, she will be researching transsexualism to see how to handle it.

Should I give her a few days before hanging out with her?

it depends.. some people would rather just talk about it with you.. rather then do research. I'm sure she wouldn't mind having you over.. she seems awesome!

Grats on your sister.  Mine was similar, she practically threw a party, but she and I were close growing up so thats to be expected, she also mentioned this:

"Your late, i asked santa for a baby sister a long time ago...."

Thanks, she sent me a text a few minutes ago checking in on me. She wants me to come out to my brother (her husband) since he is overseas. I'm not so sure what to do... I don't know if I'm ready to tell him yet. I wont mind telling him about me being into men, but the TS part, I can just see him blowing up and telling me never to come around his kids again....

Congratz on the Sister-in-law.

Talk to SIL and see what she might think.  Obviously she feels that he would be fine to have a sister.

Just saying.

Janet, we talked about it last night. She said he would be fine with it. But when I said, "I can just see him looking at me with breasts and being like DON'T LET THAT FREAK NEAR MY KIDS ANYMORE!!", she paused for a moment. I knew that she had a bit of agreement with me on that. She can say the most supportive things in the world about what his reaction may be now, but I know that pause she gave me was recognition that I could be correct in my assumption.

we never know how another will react.  He may well say that or he may well just tell the kids that Uncle Joe in now Aunt Joanne.

I hope for the best for you with the brother.