Bernadette
To me there are separate considerations/issues here and your decisions shouldn't be made by linking those separate issues.
1. Babysitting your grandchild which you enjoy! It gives YOU pleasure
2.Not being appreciated/being taken for granted
3.Time spent with other grandmother etc
So here are some questions for you to consider maybe. The answers if honest might be helpful to you in deciding a way forward. No need to answer them on here unless you choose to though; more about you focusing your thinking and separating out the different areas for consideration
1. Why do you babysit your GC? Is it to
- help your daughter and SIL?
- to build a relationship with your GC?
- because you enjoy it?
- to be appreciated?
Probably a bit of all of those but then which is MOST important to you?
2.Before you babysitting, did your family/daughter share gifts, invite each other over etc?
- Was that normal family practice?
- Is the present scenario just a carry on with what was normal pre GC arrival?
- what did you do at XMAS pre GC?
- Who made the arrangements?
- Is present non arranging with you etc the same as previously?
- Have you changed your role in making those arrangements? if so, why?
- Did you used to do things together pre GC?
- Are you expecting something different now? If so why?
- Have things changed since you started babysitting?
- Did you do things together pre your daughter getting married?
- Are you doing anything directly to create opportunities to spend time together? Inviting over? Suggesting outings? Take out for a meal? Chat on telephone?
- Do you show appreciation of what if anything is done for you? A small gift etc as that is what you see as a way of showing appreciation and you feel is missing?
- Do you ever ask for help so you can demonstrate appreciation from your perspective?
3.Time spent with other grandmother etc
- Has it always been like that?
- If so did you mind it before you started babysitting?
- Have you built any relationship with your daughter's in laws? Would that help? (sometimes does; sometimes doesn't! only you can decide)
- Is the in-laws relationship with SIL/daughter actually relevant to your relationship with them?
- Was your family dynamic/relationships ever like the one they appear to have?
- What does your husband think of all this?
- Is he your daughters stepfather? - I
- Is there a link to this behaviour if her father is not on scene/history regarding relationships/step fathers arrival etc
I hope that these questions considered and answered truthfully might help you to see the wood for the trees and find a way forward that works for you.
Finally, you referred in your OP to "I am heartbroken and feel like cutting free and saying I am not having the granddaughter anymore". I truly hope that by that you did not mean breaking off relationships; that really would be cutting off your nose to spite your face and would be your loss! 
Reform UK’s Richard Tice allegedly failed to pay £100,000 in corporation tax


